METHOD OF COMMUNICATION AND COMMUNICATION DEVICE

Description

1 / 81 METHOD OF COMMUNICATION AND COMMUNICATION DEVICE TECHNICAL FIELD

[001] This application relates to the field of communication technologies and, in particular, to a method of communication and a communication device. BACKGROUND

[002] A sidelink user equipment-to-network relay (SL U2N Relay) is a technology in which one UE assists another UE in communicating with a base station, also known as relay technology. The U2N relay communication architecture includes a remote device (remote UE), a relay device (relay UE), and a base station. The base station includes a distributed unit (DU) and a central unit (CU). For example, the CU and the DU are connected via an F1 interface. The relay UE is connected to the DU, and the corresponding interface is a Uu interface. The remote UE and the relay UE are directly connected (e.g., connected via a sidelink), and the corresponding interface is a PC5 interface.For example, in a split CU-DU architecture, when the remote UE requests, via the relay UE, the re-establishment of a radio resource control (RRC) connection or the resumption of an RRC connection, the way the DU forwards a re-establishment or resumption of RRC connection message to the relay UE and / or the remote UE becomes a problem to be solved. SUMMARY

[003] This application provides a method of communication and a communication device. In the method, an access network device can correctly forward an initial re-establishment or resumption of connection message, so that the remote UE Petition 870250104104, dated 11 / 13 / 2025, page 8 / 102 2 / 81 can correctly access a corresponding access network device when performing the first RRC restoration / resumption via the relay UE.

[004] According to a first aspect, this application provides a method of communication, and the method is applied to a first network device. The first network device may be an access network device. The first network device may be a distributed unit, or it may be a component (e.g., a processor, a chip, or a system-on-a-chip) of the access network device, or it may be a logic module that may implement all or some functions of the distributed unit. The first network device receives indication information from a second network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier. The first network device receives a first message from the second network device and transmits the first message based on the first mapping relationship.The first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit the first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between a second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device.

[005] In this method, the first network device (e.g., a DU) receives the indication information and determines, based on the indication information, a configuration of the first mapping relationship used to transmit the first message, Petition 870250104104, dated 11 / 13 / 2025, page 9 / 102 3 / 81 so that the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses a corresponding access network device. Optionally, the mapping relationship in this application may also be called mapping configuration.

[006] In one possible implementation, the first network device receives the first indication information from the second network device, wherein the first indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an interface between the first network device and the second network device. For example, the first identifier is used to identify the first terminal device on an F1 interface between the first network device and the second network device, and the first network device can associate with the first terminal device based on the first identifier.

[007] In one possible implementation, the first terminal device may re-establish or resume the first connection via an associated relay terminal device before re-establishing or resuming the first connection. In this case, the first indication information received by the first network device carries the first identifier of the first terminal device (e.g., an old gNB-DU UE UE F1AP remote ID). This helps the first network device obtain context information from the first terminal device.

[008] In one possible implementation, the first network device obtains context information from the first terminal device based on the first identifier, and determines the first mapping relationship based on the context information from the first terminal device. Petition 870250104104, dated 11 / 13 / 2025, page 10 / 102 4 / 81

[009] In this method, if the first terminal device re-establishes or resumes the first connection via the relay terminal device associated with the first terminal device before the first connection is re-established or resumed, the first network device can look up the context information of the first terminal device based on the first identifier. The context information includes a previously configured mapping relationship between an SRB1 and a Uu relay RLC channel (for example, a mapping relationship between the SRB1 and the Uu relay RLC channel and configured by the remote UE before the first connection is re-established or resumed). The first network device can use the previously configured mapping relationship as the first mapping relationship.This helps the first terminal device to re-establish or resume the initial connection and correctly access a corresponding network access device.

[010] In one possible implementation, the first network device determines the first mapping relationship based on the second indication information and the context information of the first terminal device, where the second indication information indicates the first network device to apply the first mapping relationship.

[011] In this method, if the first terminal device re-establishes or resumes the first connection via the relay terminal device associated with the first terminal device before the first connection is re-established or resumed, the second network device can indicate to the first network device that the previously configured mapping relationship between SRB1 and the Uu relay RLC channel is used as the first mapping relationship. This helps the first terminal device to re-establish or resume the first connection and access Petition 870250104104, dated 11 / 13 / 2025, page 11 / 102 5 / 81 correctly a matching network access device.

[012] In one possible implementation, the first network device determines the first mapping relationship based on the first identifier of the first terminal device, the context information of the first terminal device, and the corresponding information of the second terminal device. For example, the corresponding information of the second terminal device includes one or more of the following: a second identifier of the second terminal device, service information of the second terminal device, and context information of the second terminal device.

[013] In the method, the first network device can determine, based on the first identifier and corresponding information of the second associated terminal device (e.g., a UE F1AP relay ID of the associated relay UE, historical service information, and UE context information of the second terminal device), that the first terminal device performs the access by re-establishing the first connection or resuming the previously associated relay terminal device. Therefore, the first network device can use the previously configured mapping relationship between SRB1 and the Uu relay RLC channel as the first mapping relationship, to help the first terminal device re-establish or resume the first connection and correctly access a corresponding access network device.

[014] In a possible implementation, the indication information includes the first mapping relationship.

[015] In the method, the indication information received by the first network device includes a new mapping relationship between SRB1 and the Uu relay RLC channel. The first network device uses the new mapping relationship between SRB1 and the Uu relay RLC channel. Petition 870250104104, dated 11 / 13 / 2025, page 12 / 102 6 / 81 as the first mapping relationship, so that the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses a corresponding access network device.

[016] In one possible implementation, the first network device determines, based on the first identifier of the first terminal device and the corresponding information of the second terminal device, the release of a second mapping relationship. The second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[017] In the method, the first network device can determine, based on the second identifier (e.g., a relay UE F1AP ID of the new relay UE), that the first terminal device performs access via the second terminal device (the new relay UE). Since the context information of the first terminal device also includes another mapping relationship (namely, the second mapping relationship), for example, the second mapping relationship includes a mapping relationship originally configured between an SRB2 / DRB and the relay RLC channel of Uu, the first network device can release the second mapping relationship.

[018] In one possible implementation, the first network device receives third-party indication information from the second network device, wherein the third-party indication information tells the first network device to release a second mapping relationship, the second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[019] In this method, the second network device can tell the first network device to release the second connection. Petition 870250104104, dated 11 / 13 / 2025, page 13 / 102 7 / 81 mapping. When the first network device receives the third indication information, the first network device can release the originally configured mapping relationship between SRB2 / DRB and the Uu relay RLC channel based on an indication.

[020] In one possible implementation, the first network device receives a request message to establish or update context information from the second network device, where the request message to establish or update context information is used to set up a second mapping relationship, and the second mapping relationship is different from the first mapping relationship.

[021] In this method, as the first network device determines to release another originally configured mapping relationship, the first network device can reconfigure the second mapping relationship of the first terminal device based on a context information establishment or update procedure triggered by the second network device. This helps the first terminal device to re-establish or resume the first connection through the second terminal device and to correctly access a corresponding access network device.

[022] In one possible implementation, the first downlink message is a first reconnection message, a first reconnection message, or a first connection release message; and the first carrier is an SRB1 signaling radio carrier message from the first terminal device.

[023] In one possible implementation, the first downlink message is a first connection establishment message, and the first carrier is an SRB0 message from the first terminal device. Petition 870250104104, dated 11 / 13 / 2025, page 14 / 102 8 / 81

[024] In one possible implementation, the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first terminal device.

[025] According to a second aspect, this application provides another method of communication, and the method is applied to a second network device. The second network device may be an access network device. The second network device may be a central unit, or it may be a component (e.g., a processor, a chip, or a system-on-a-chip) of the access network device, or it may be a logic module that may implement all or some functions of the central unit. The second network device sends indication information to a first network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier.The second network device sends a first message to the first network device, where the first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit a first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between a second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device.

[026] In this method, the second network device sends the indication information to the first network device, so that the first network device can determine, based on the indication information, a configuration of the first Petition 870250104104, dated 11 / 13 / 2025, page 15 / 102 9 / 81 mapping relationship used to transmit the first message, and the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses a corresponding access network device.

[027] In one possible implementation, the second network device sends first indication information to the first network device, where the first indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an interface between the first network device and the second network device.

[028] In one possible implementation, the first terminal device may re-establish or resume the first connection via an associated relay terminal device prior to the first re-establishment or resumption of connection. In this case, the associated relay terminal device prior to the first re-establishment or resumption of connection may indicate the first identifier of the first terminal device to the first network device. This helps the first network device obtain context information from the first terminal device.

[029] In one possible implementation, the first identifier of the first terminal device is used by the first network device to obtain the context information of the first terminal device, and the context information of the first terminal device includes the first mapping relationship.

[030] In this method, if the first terminal device re-establishes or resumes the first connection via an associated relay terminal device before the first re-establishment or resumption of connection, the information Petition 870250104104, dated 11 / 13 / 2025, page 16 / 102 The 10 / 81 context of the first terminal device includes a mapping relationship that is between an SRB1 and a Uu relay RLC channel, configured by the remote UE before the first re-establishment or resumption of connection. The mapping relationship can be used as the first mapping relationship to assist the first terminal device in re-establishing or resuming the first connection and correctly accessing a corresponding access network device.

[031] In one possible implementation, the second network device determines, based on the second message and a second identifier of the second terminal device, the relay terminal device associated with the first terminal device before the procedure to re-establish or resume the first connection. The second message is used by the first terminal device to request the procedure to re-establish or resume the first connection.

[032] In the method, the second network device can determine, based on the second message and the corresponding information from the second terminal device, that the first terminal device accesses the relay terminal device associated with the first terminal device before the first re-establishment or resumption of connection.

[033] In one possible implementation, the second network device sends second indication information to the first network device, where the second indication information tells the first network device to apply the first mapping relationship.

[034] In the method, if the first terminal device re-establishes or resumes the first connection through the relay terminal device associated with the first terminal device before the re-establishment or resumption of the first connection procedure, the second network device can indicate to the first network device that a relationship of Petition 870250104104, dated 11 / 13 / 2025, page 17 / 102 The previously configured 11 / 81 mapping between SRB1 and the Uu relay RLC channel is used as the first mapping link. This helps the first terminal device to re-establish or resume the initial connection and correctly access a corresponding access network device.

[035] In a possible implementation, the indication information includes the first mapping relationship.

[036] In the method, the indication information sent by the second network device includes a new mapping relationship between SRB1 and the Uu relay RLC channel (different from the previously configured mapping relationship between SRB1 and the Uu relay RLC channel), to help the first terminal device re-establish or resume the first connection through the second terminal device and correctly access a corresponding access network device.

[037] In one possible implementation, the second network device determines, based on a second message and a second identifier of the second terminal device, that a relay terminal device associated with the second terminal device is different from a relay terminal device associated with the first terminal device before a first connection re-establishment or resumption procedure, wherein the second message is used by the first terminal device to request the re-establishment or resumption of the first connection. The second network device determines to update the first mapping relationship.

[038] In the method, the second network device can determine, based on the second message and the corresponding information from the second terminal device, that the first terminal device performs access through the second terminal device (new relay UE), and the first mapping relationship needs to be updated. Petition 870250104104, dated 11 / 13 / 2025, page 18 / 102 12 / 81

[039] In one possible implementation, the second network device sends third indication information to the first network device, wherein the third indication information indicates that the first network device should release a second mapping relationship, the second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[040] In the method, the second network device can indicate to the first network device to release the second mapping relationship, so that the first network device can release the second mapping relationship based on the indication, for example, releasing a mapping relationship originally configured between an SRB2 / a DRB and a Uu relay RLC channel.

[041] In one possible implementation, the second network device sends a request message to establish or update context information from the first terminal device to the first network device, where the request message to establish or update context information is used to set up a second mapping relationship, and the second mapping relationship is different from the first mapping relationship.

[042] In the method, assuming that the first terminal device performs access through the second terminal device, the second network device determines that a mapping relationship different from the first mapping relationship needs to be updated. For example, updating the second mapping relationship in a context information establishment or update procedure includes: sending a context information establishment or update request message from the first terminal device to the second network device, thus facilitating the correct transmission of Petition 870250104104, dated 11 / 13 / 2025, page 19 / 102 13 / 81 data between the first terminal device and the second terminal device.

[043] In one possible implementation, the second network device sends the first configuration information to the second terminal device, where the first configuration information includes the first mapping relationship. Optionally, the first configuration information also includes a third mapping relationship between the first carrier and a third carrier, and the third carrier is used to transmit the first message between the first terminal device and the second terminal device.

[044] In the method, the second network device can configure a first remapped mapping relationship for the new relay UE, in order to assist the first terminal device in correctly transmitting data between the second terminal device and the first terminal device. Optionally, the second network device can also reconfigure a third mapping relationship (for example, a mapping relationship between SRB1 and a relay RLC channel of PC5).

[045] In one possible implementation, the first downlink message is a first reconnection message, a first reconnection message, or a first connection release message; and the first carrier is an SRB1 signaling radio carrier message from the first terminal device.

[046] In one possible implementation, the first downlink message is a first connection establishment message, and the first carrier is an SRB0 message from the first terminal device.

[047] In one possible implementation, the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first Petition 870250104104, dated 11 / 13 / 2025, page 20 / 102 14 / 81 terminal device.

[048] According to a third aspect, this application provides a communication apparatus. The communication apparatus may be an access network device (e.g., a DU), an access network device apparatus, or an apparatus that can be used in conjunction with an access network device. In one possible implementation, the communication apparatus may include a functional module. The functional module may be implemented by a hardware circuit, software, or a combination of a hardware circuit and software.

[049] In one possible implementation, the communication apparatus includes a communication unit and a processing unit. The communication unit is configured to receive indication information from a second network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier. The communication unit is further configured to receive a first message from the second network device. The processing unit is configured to transmit the first message based on the first mapping relationship through the communication unit.The first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit the first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between a second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device. Petition 870250104104, dated 11 / 13 / 2025, page 21 / 102 15 / 81

[050] In one possible implementation, the communication unit is configured to receive indication information from the second network device, including: receive initial indication information from the second network device, wherein the initial indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an F1 interface between the first network device and the second network device.

[051] In one possible implementation, the processing unit is configured to determine the first mapping relationship between the first carrier and the second carrier, including: Obtain context information from the first terminal device based on the first identifier; and determine the first mapping relationship based on the context information from the first terminal device.

[052] In one possible implementation, the processing unit is configured to determine the first mapping relationship based on context information from the first endpoint device, including: To determine the first mapping relationship based on the second indication information and the context information of the first terminal device, where the second indication information indicates the first network device to apply the first mapping relationship.

[053] In one possible implementation, the processing unit is configured to determine the first mapping relationship based on context information from the first endpoint device, including: determine the first mapping relationship based on the first identifier of the first terminal device, in Petition 870250104104, dated 11 / 13 / 2025, page 22 / 102 16 / 81 context information of the first terminal device and in the corresponding information of the second terminal device, wherein the corresponding information of the second terminal device includes one or more second terminal device identifiers, second terminal device service information and second terminal device context information.

[054] In a possible implementation, the indication information includes the first mapping relationship.

[055] In one possible implementation, the processing unit is further configured to determine, based on the first identifier of the first terminal device and the corresponding information of the second terminal device, the release of a second mapping relationship. The second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[056] In one possible implementation, the communication unit is further configured to receive third-party indication information from the second network device, wherein the third-party indication information tells the first network device to release a second mapping relationship, the second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[057] In one possible implementation, the communication unit is further configured to receive a request message to establish or update context information from the second network device, where the request message to establish or update context information is used to configure a second mapping relationship, and the second mapping relationship is different from the first relationship. Petition 870250104104, dated 11 / 13 / 2025, page 23 / 102 17 / 81 mapping.

[058] In one possible implementation, the first downlink message is a first reconnection message, a first reconnection message, or a first connection release message; and the first carrier is an SRB1 signaling radio carrier message from the first terminal device.

[059] In one possible implementation, the first downlink message is a first connection establishment message, and the first carrier is an SRB0 message from the first terminal device.

[060] In one possible implementation, the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first terminal device.

[061] According to a fourth aspect, this application provides another communication apparatus. The communication apparatus may be an access network device (e.g., a CU), an apparatus of the access network device, or an apparatus that can be used in conjunction with the access network device. In one possible implementation, the communication apparatus may include a functional module. The functional module may be implemented by a hardware circuit, software, or a combination of a hardware circuit and software.

[062] In one possible implementation, the communication device may include a communication unit and a processing unit. The communication unit is configured to send indication information to the first network device, wherein the indication information is used to determine the first mapping relationship between the first carrier and the second carrier. The communication unit is further configured to send a first message to the first network device, wherein the first message is a first message of Petition 870250104104, dated 11 / 13 / 2025, page 24 / 102 18 / 81 downlink sent by the second network device to the first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit a first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between the second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device.

[063] In one possible implementation, the communication unit is configured to send the indication information to the first network device, including: Send the first indication information to the first network device, where the first indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an F1 interface between the first network device and the second network device.

[064] In one possible implementation, the first identifier of the first terminal device is used by the first network device to obtain the context information of the first terminal device, and the context information of the first terminal device includes the first mapping relationship.

[065] In one possible implementation, the processing unit is configured to determine, based on a second message and a second identifier of the second terminal device, that the second terminal device is a relay terminal device associated with the first terminal device before the re-establishment procedure. Petition 870250104104, dated 11 / 13 / 2025, page 25 / 102 19 / 81 or resumption of the first connection. The second message is used by the first terminal device to request the procedure for re-establishing or resuming the first connection.

[066] In one possible implementation, the communication unit is configured to send the indication information to the first network device, including: Send secondary indication information to the first network device, where the secondary indication information tells the first network device to apply the first mapping relationship.

[067] In a possible implementation, the indication information includes the first mapping relationship.

[068] In one possible implementation, the processing unit is further configured to determine, based on a second message and a second identifier of the second terminal device, that a relay terminal device associated with the second terminal device is different from a relay terminal device associated with the first terminal device before the first connection re-establishment or resumption procedure, wherein the second message is used by the first terminal device to request the re-establishment or resumption of the first connection. The processing unit is further configured to determine the update of the first mapping relationship.

[069] In one possible implementation, the communication unit is further configured to send third-party indication information to the first network device, wherein the third-party indication information tells the first network device to release a second mapping relationship. The second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship.

[070] In a possible implementation, the communication unit Petition 870250104104, dated 11 / 13 / 2025, page 26 / 102 20 / 81 is further configured to send a request message to establish or update context information to the first terminal device, where the request message to establish or update context information is used to configure a second mapping relationship, and the second mapping relationship is different from the first mapping relationship.

[071] In one possible implementation, the communication unit is further configured to send the first configuration information to the second terminal device, where the first configuration information includes the first mapping relationship. Optionally, the first configuration information also includes a third mapping relationship between the first carrier and a third carrier, and the third carrier is used to transmit the first message between the first terminal device and the second terminal device.

[072] In one possible implementation, the first downlink message is a first reconnection message, a first reconnection message, or a first connection release message; and the first carrier is an SRB1 signaling radio carrier message from the first terminal device.

[073] In one possible implementation, the first downlink message is a first connection establishment message, and the first carrier is an SRB0 message from the first terminal device.

[074] In one possible implementation, the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first terminal device.

[075] According to a fifth aspect, this application provides a communication apparatus, including a processor, configured to execute instructions. Optionally, the apparatus Petition 870250104104, dated 11 / 13 / 2025, page 27 / 102 The 21 / 81 communication system also includes a memory. The memory is configured to store instructions. When the instructions are executed by the processor, the communication device is enabled to implement the method according to any of the first aspects and the possible implementations of the first aspect. Optionally, the processor is coupled to the memory.

[076] According to a sixth aspect, this application provides a communication apparatus, including a processor, configured to execute instructions. Optionally, the communication apparatus also includes a memory. The memory is configured to store the instructions. When the instructions are executed by the processor, the communication apparatus is enabled to implement the method according to either of the second aspect and the possible implementations of the second aspect. Optionally, the processor is coupled to the memory.

[077] According to a seventh aspect, this application provides a communication system. The communication system includes a plurality of apparatuses or devices according to the third to sixth aspects. The apparatuses or devices are enabled to perform the methods according to the first and second aspects and any of the possible implementations of the first and second aspects.

[078] According to an eighth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are run on a computer, the computer is enabled to perform the methods according to the first and second aspects and any of the possible implementations of the first and second aspects.

[079] According to a ninth aspect, this application provides a chip. The chip includes a processor and an interface and, optionally, may also include memory, configured to implement the method according to any of the first ones. Petition 870250104104, dated 11 / 13 / 2025, p. 28 / 102 22 / 81 aspect, second aspect and the possible implementations of the first and second aspects.

[080] According to a tenth aspect, this application provides a chip system. The chip system includes a processor and an interface and may optionally include memory, configured to implement the method according to any of the first aspect, the second aspect, and the possible implementations of the first and second aspects. The chip system may include a chip or it may include a chip and another discrete component.

[081] According to an eleventh aspect, this application provides a computer program product, including instructions. When the instructions are run on a computer, the computer is enabled to perform the method in either of the first and second aspects, and the possible implementations of the first and second aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[082] Figure 1 is a diagram of a communication system according to this request; Figure 2 is a diagram of a user plane protocol stack of an L2 U2N relay; Figure 3 is a diagram of a remote UE downlink data routing process; Figure 4 is a diagram of a CU-DU split architecture; Figure 5 is a diagram of user-plane and control-plane protocol stacks in a split CUDU architecture; Figure 6A and Figure 6B are a schematic flowchart of RRC connection re-establishment performed by UE in a split CU-DU architecture; Figure 7 is a schematic flowchart of a communication method in accordance with this request; Figure 8 is a schematic flowchart of another method of Petition 870250104104, dated 11 / 13 / 2025, page 29 / 102 23 / 81 communication in accordance with this request; Figure 9 is a schematic flowchart of another communication method in accordance with this request; Figure 10A and Figure 10C are a schematic flowchart of another communication method in accordance with this request; Figure 11 is a diagram of a communication device according to this application; and Figure 12 is a diagram of another communication device according to this application. DESCRIPTION OF THE MODALITIES

[083] In the modalities of this request, / may represent a relationship between associated objects. For example, A / B may represent A or B. and / or may be used to indicate that there are three relationships between associated objects. For example, A and / or B may represent the following three cases: Only A exists, A and B exist, and only B exists, where A and B may be singular or plural. To facilitate the description of technical solutions in the modalities of this request, words such as first and second may be used to distinguish technical resources with equal or similar function. Words such as first and second do not limit a quantity and sequence of execution, and words such as first and second do not limit a definite difference. In the modalities of this request, words such as example or for example are used to represent an example, evidence, or description.Any design approach or solution described as an example or by way of example should not be explained as being more preferable or having more advantages than another design approach or solution. A word like "example" or "by way of example" is used to present a related concept in a specific way to facilitate understanding.

[084] The following describes the technical solutions in embodiments of this application with reference to the drawings attached in embodiments of this application. Petition 870250104104, dated 11 / 13 / 2025, p. 30 / 102 24 / 81

[085] To address the problem of how a DU forwards a first downlink message to the relay UE and / or remote UE in a remote UE RRC connection re-establishment / resume scenario, this application provides a communication method. In the method, a gNB-DU can apply an SRB1 mapping relationship configuration in the original context of the remote UE or obtain an SRB1 mapping relationship configuration based on the indication of a gNBCU, so that the remote UE correctly accesses a DU and a CU when performing RRC re-establishment / resume using the relay UE.

[086] The communication method provided in this application can be applied to a communication system shown in Figure 1. For example, the communication system includes network devices (e.g., a gNB-DU and a gNB-CU), a relay device (e.g., a relay UE), and a remote device (e.g., a remote UE). The network devices include a distributed unit DU and a central unit CU, and the CU and DU communicate with each other via an F1 interface. The relay device and the remote device can be terminal devices. For example, the relay device communicates with the remote device via a PC5 interface, and the relay device communicates with the network device via a Uu interface, as shown in Figure 1.Optionally, in this application, the remote device may also be referred to as a first terminal device, and the relay device may also be referred to as a second terminal device. In one possible implementation, the network device is an access network device that provides a user access function, such as a base station. The network device and the terminal device may perform signal / data transmission. Optionally, the communication method provided in this application is also applicable. Petition 870250104104, dated 11 / 13 / 2025, page 31 / 102 25 / 81 refers to a scenario where the remote device communicates with the network device via relays from a plurality of relay devices. Figure 1 is merely an example and does not limit the solutions of this application.

[087] The communication system in this application may include, but is not limited to, a communication system that utilizes various radio access technologies (RATs). For example, it may be an LTE communication system; a 5G communication system (or so-called new radio (NR)); a transition system between the LTE communication system and the 5G communication system, wherein the transition system may also be referred to as a 4.5G communication system; or a future communication system, such as a 6th generation (6G) or even a 7th generation (7G) system. The network architecture and service scenario described in the embodiments of this application are intended to describe the technical solutions in the embodiments of this application more clearly and do not constitute a limitation on the technical solutions provided in the embodiments of this application.A professional with average technical knowledge will know that, with the evolution of communication network architectures and the emergence of new service scenarios, the technical solutions provided in the modalities of this request are also applicable to similar technical problems.

[088] A terminal device, also known as user equipment (UE), mobile station (MS), mobile terminal (MT), or similar, is a device that provides voice and / or data connectivity to a user, for example, a portable device or a vehicle-mounted device with wireless connectivity. Currently, for example, a terminal device is a mobile phone, a tablet computer, a notebook computer, a palmtop computer, a mobile internet device (MID), a device Petition 870250104104, dated 11 / 13 / 2025, page 32 / 102 26 / 81 wearable, an unmanned aerial vehicle, a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transport safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a terminal device in a 5G network, a terminal device in a future evolved PLMN network, a terminal device in a future communication system, or similar.

[089] A network device is a radio access network (RAN) node (or device) that connects the terminal device to a wireless network, for example, it could be a base station. For example, a RAN node is a continuously evolved NodeB (gNB), a transmission reception point (TRP), an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved NodeB or a home NodeB, HNB), a baseband unit (BBU), a wireless fidelity access point (AP), a satellite in a satellite communication system, a radio controller in a cloud radio access network (CRAN) scenario.a wearable device, an unmanned aerial vehicle, a device in a vehicle internet (e.g., a vehicle-to-everything (V2X) device), a device-to-device communication device, Petition 870250104104, dated 11 / 13 / 2025, p. 33 / 102 27 / 81 (D2D) or similar. The access network device may include a central unit (CU) node, a distributed unit (DU) node, or a RAN device including a CU node and a DU node. Possibly, a RAN device including a CU node and a DU node divides the protocol layer of an eNB in ​​a long-term evolution (LTE) system. The functions of some protocol layers are centrally controlled by the CU, and the functions of some or all of the remaining protocol layers are distributed across the DU. The CU centrally controls the DU.

[090] In one possible scenario, a plurality of RAN nodes cooperatively assist a terminal in implementing wireless access, and different RAN nodes separately implement some functions of a base station. For example, the RAN node can be a CU, a DU, a CU control plane (CP), a CU user plane (UP), or a radio unit (RU). The CU and DU can be arranged separately or can be included in the same network element, for example, a baseband unit (BBU). The RU can be included in a radio frequency device or in a radio frequency unit, for example, in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[091] In different systems, the CU (or the CU-CP and CU-UP), the DU, or the RU may alternatively have different names, but a person skilled in the art can understand their meanings. For example, in an ORAN system, the CU may also be called an open-radio CU (O-CU), the DU may also be called O-DU, the CU-CP may also be called O-CU-CP, the CU-UP may also be called O-CU-UP, and the RU may also be called O-RU. For ease of description, the CU, CU-CP, CU-UP, DU, and RU are used as examples for description in this document. Petition 870250104104, dated 11 / 13 / 2025, page 34 / 102 28 / 81 application. Any of the CU (or CU-CP or CU-UP), DU, and RU in this application may be implemented using a software module, a hardware module, or a combination of a software module and a hardware module.

[092] The access network device in some embodiments may alternatively be an open-radio access network (O-RAN) device, and the O-RAN device may include an O-DU and an O-CU. In embodiments of this application, a base station function may be performed by a module (e.g., a chip) in the base station or may be performed by a control subsystem that includes a base station function. The control subsystem, including the base station function, may be a control center in the application scenarios mentioned above, such as a smart grid, industrial control, smart transportation, and a smart city. A specific technology and a specific device form factor used by the radio access network device are not limited in embodiments of this application.To facilitate the description, an example is presented below in which the base station is used as a radio access network device for descriptive purposes.

[093] I. For ease of understanding, the definitions of the terms related to this application are described in detail below. 1. Sidelink communication

[094] In a wireless communication system, UEs can perform data communication through a network device or they can communicate directly with each other without relying on a network device. An interface between UEs is called a PC5 interface, similar to a Uu interface between the UE and a base station. A link between UEs is called a side link. For example, a typical application scenario for side link communication is vehicle-to-everything (V2X). In vehicle-to-everything, it is assumed that each vehicle represents Petition 870250104104, dated 11 / 13 / 2025, page 35 / 102 29 / 81 an UE, and the data can be transmitted directly between the UEs via a side link without using a network. In this way, communication delays can be effectively reduced. For example, the relay device and the remote device in the communication system shown in Figure 1 can communicate directly with each other via a side link.

[095] Specifically, the side link supports broadcast communication, unicast communication, and multicast communication. Broadcast communication is similar to the broadcast transmission of system information by a base station. Specifically, the UE sends broadcast service data to the outside without encryption, and any other UE within an effective reception range can receive the broadcast service data if the UE is interested in a broadcast service. Unicast communication is similar to data communication performed after establishing an RRC connection between the UE and a base station, and a unicast connection needs to be established first between two UEs. After establishing the unicast connection, the two UEs can perform data communication based on a negotiated identifier. The data may or may not be encrypted.Compared to broadcast communication, unicast communication can only be performed between two UEs between which a unicast connection has been established. Multicast communication is communication between all UEs in a communication group, and any UE in the group can receive and send data from a multicast service.

[096] Unicast communication on the side link corresponds to a pair of a source L2 ID (layer-2 identifier) ​​and a destination L2 ID. A subheader of a media access control protocol data unit (MAC PDU) for each side link includes the source L2 ID and the destination L2 ID, so that the data can be Petition 870250104104, dated 11 / 13 / 2025, p. 36 / 102 30 / 81 transmitted from a transmitter to a correct receiver. 2. Radio bearer (RB)

[097] The radio carrier is a general term for a series of entities and protocol configurations allocated by a base station to the UE, being a service provided by layer 2 and used to transmit user data between the UE and the base station. The radio carrier includes a packet data convergence protocol (PDCP) entity, a radio link control (RLC) entity, a series of resources allocated by a MAC protocol entity, and a physical layer (PHY), among others. The radio carrier is classified into data radio bearer (DRB) and signaling radio bearer (SRB). The DRB is used to carry data, and the SRB is used to carry a signaling message.In a sidelink communication scenario, UEs communicate with each other using a sidelink radio bearer (SLRB), and the SLRB includes a sidelink data radio bearer (SL DRB) and a sidelink signaling radio bearer (SL SRB). In a protocol text, a radio bearer configuration typically includes only configurations from a PDCP layer and a service data adaptation protocol (SDAP) layer. A protocol entity below an RLC layer is called an RLC bearer, and a corresponding configuration is provided in an RLC bearer configuration. The RLC bearer includes a protocol entity and a configuration below the RLC layer, is part of the lower layer of a radio bearer, and includes a number of features such as an RLC protocol entity and a logical channel.An RLC carrier is associated with a logical channel in a MAC layer. An RLC carrier is associated with a PDCP entity, that is, Petition 870250104104, dated 11 / 13 / 2025, p. 37 / 102 31 / 81 an RLC serves an RB radio carrier. 3. Relay technology

[098] In an existing protocol standard, an R17 side-link UE-network relay (SL U2N Relay) is a technology in which one UE assists another UE in communicating with a base station, also called relay technology. For example, the communication system shown in Figure 1 can be considered a U2N relay communication architecture, and the remote UE communicates with the base station through the cooperation of the relay UE. The remote UE and the relay UE communicate via a side link, and the corresponding interface is PC5. The relay UE and the base station are directly connected and communicate via a Uu interface.

[099] U2N relay technology includes two designs: L2 and Layer 3 (L3). This application refers primarily to the protocol architecture of an L2 U2N relay. The following describes the protocol architecture of the L2 U2N relay. For example, Figure 2 is a diagram of a user plane protocol stack of the L2 U2N relay. A data packet from the remote UE is relayed and forwarded below a PDCP layer of the relay UE. In other words, the relay UE maintains only a relay RLC carrier, including an RLC layer, a MAC layer, and a PHY layer. In other words, there are end-to-end SDAP and PDCP layers, but no end-to-end RLC, MAC, and PHY layers between the remote UE and the base station. Optionally, a U2N L2 relay control plane protocol stack is similar to that in Figure 2, with the difference that there are end-to-end RRC and PDCP layers between the remote UE and the base station.Details are not described again in this document.

[100] In addition, a sidelink relay adaptation protocol layer Petition 870250104104, dated 11 / 13 / 2025, page 38 / 102 The 32 / 81 protocol layer (SRAP) is added between the RLC layer and the PDCP layer in the protocol stack. A primary function of the SRAP layer is the multiplexing and demultiplexing of a radio carrier, that is, supporting the end-to-end multiplexing of different radio carriers onto a single RLC carrier and a corresponding demultiplexing process. An RLC carrier between the remote UE and the relay UE is called the PC5 relay RLC channel / carrier, and an RLC carrier between the relay UE and the base station is called the Uu relay RLC channel / carrier. Through multiplexing, different radio carriers from a remote UE can be multiplexed onto a single PC5 relay RLC channel. Alternatively, in a scenario where a relay UE is connected to a plurality of remote UEs, different radio carriers from one or more remote UEs can be multiplexed onto a single relay RLC channel of Uu.

[101] During downlink transmission, the base station's SRAP layer can multiplex data on a plurality of radio carriers from one or more remote UEs onto a Uu retransmission RLC carrier. On a sidelink of each remote UE, data on one or more radio carriers of the remote UE can be mapped to a PC5 retransmission RLC carrier. Similarly, during uplink transmission, the remote UE's SRAP layer can map data on a plurality of radio carriers from the remote UE to a PC5 retransmission RLC carrier. A retransmission UE adaptation layer can multiplex data on different radio carriers from one or more remote UEs onto a Uu retransmission RLC carrier to implement carrier multiplexing.

[102] To distinguish between data from different remote UEs, the base station allocates a remote UE ID, also known as a local identifier (local ID), to each remote UE, and the local ID is ported in a data packet routing process to Petition 870250104104, dated 11 / 13 / 2025, page 39 / 102 33 / 81 identify the remote UE to which the data belongs. An existing protocol specifies that the local ID of the remote UE is allocated by a base station where the relay UE is located, and the allocated local ID can be unique to the base station or the relay UE. In one possible implementation, after the remote UE establishes a unicast connection with the relay UE, the relay UE sends an RRC message (e.g., a SidelinkUEInformationNR (SUI) message) to the base station, where the message carries an L2 ID of the remote UE, used to request that the base station allocate a local ID to the remote UE.

[103] Before data transmission, the base station performs SRAP configuration for the remote UE and relay UE for data routing. The SRAP configuration may include a mapping relationship between a radio carrier ID (an RB ID, including an SRB ID / DRB ID) of the remote UE and a Uu relay RLC channel / PC5 ​​relay RLC channel. Specifically, the base station configures a mapping relationship between a radio carrier (an SRB or a DRB) and a PC5 relay RLC channel for the remote UE, and configures a local ID of the remote UE and a mapping relationship between a radio carrier of the remote UE and a Uu / PC5 relay RLC channel for the relay UE. When sending uplink or downlink data, the remote UE or the base station adds the local ID and RB ID of the remote UE to an SRAP header.Based on the SRAP configuration, the remote UE data can be correctly relayed and forwarded by the relay UE.

[104] For example, Figure 3 is a diagram of a downlink data routing process from the remote UE. The base station's SRAP layer receives a PDCP PDU from remote UE 1 from the PDCP layer, adds a local ID of remote UE 1 and ID information of a radio carrier (an SRB or a DRB) to the SRAP header, and delivers the PDCP PDU to the relay RLC channel of Petition 870250104104, dated 11 / 13 / 2025, page 40 / 102 34 / 81 Based on a mapping relationship configuration, after receiving a data packet from the Uu relay RLC channel, a relay UE adaptation layer can deliver the data packet to a correct PC5 relay RLC channel based on a mapping relationship configured by the base station. After receiving the data packet from the PC5 relay RLC channel, the remote UE delivers, based on the carrier ID information in the SRAP header, the data packet to a corresponding PDCP layer for processing. Optionally, an uplink data routing process is similar to a downlink data routing process. Details are not described again in this document. 4. CU-DU Split Architecture

[105] For example, Figure 4 is a diagram of a CU-DU split architecture. The architecture includes a 5G core network and a next-generation radio access network (NG-RAN). The NG-RAN includes a series of gNBs (including a gNB-CU and a gNB-DU) connected to the 5G core network. The gNB is connected to the 5G core network via an NG interface, and the gNBs are connected to each other via an Xn interface. Specifically, in the CU-DU split architecture, a gNB can be split into a gNB-CU and one or more gNB-DUs. The gNBCU and the gNB-DU are connected via an F1 interface.

[106] In one possible implementation, for example, in the CU-DU split architecture, gNB-CU is responsible for the RRC, SDAP and PDCP protocol layers, and gNB-DU is responsible for the RLC, MAC and PHY protocol layers. In another example, for a control plane (control plane, CP), a gNB-CU-CP is responsible for RRC and a PDCP entity corresponding to an SRB; and for a user plane (user plane, UP), a gNB-CU-UP is responsible for an SDAP and a PDCP entity corresponding to a DRB. Petition 870250104104, dated 11 / 13 / 2025, p. 41 / 102 35 / 81

[107] For example, in the CU-DU split architecture, a CU-DU split architecture protocol stack is shown in Figure 5. The protocol stack includes, but is not limited to, the following design principles.

[108] (1) SRAP is located on the DU side.

[109] (2) gNB-CU determines a mapping relationship configuration in the SRAP layer.

[110] (3) gNB-DU determines a PC5 / Uu relay RLC channel configuration based on an indication from gNB-CU.

[111] (4) The gNB-CU allocates a local ID of the remote UE.

[112] (5) An SRAP layer configuration and PC5 relay RLC channel configuration are performed for the remote UE using an F1AP message from the remote UE (the message carries an identifier (F1AP ID) from the remote UE on an F1 interface and is used to generate a related configuration from the remote UE).

[113] (6) The SRAP layer configuration and the PC5 / Uu relay RLC channel configuration are performed for the relay UE using a relay UE F1AP message (the message carries a relay UE identifier on the F1 interface and is used to generate a related relay UE configuration).

[114] It should be noted that the CU-DU split architecture and protocol stack shown in Figure 4 and Figure 5 are merely exemplary. The splitting method or the name of the protocol stack are not limited to this application.

[115] 5. In the CU-DU split architecture, a procedure in which the UE performs the re-establishment of the RRC connection is as follows.

[116] For example, Figure 6A and Figure 6B are a schematic flowchart of the RRC connection re-establishment performed by UE in the CU-DU split architecture. The procedure includes the following steps.

[117] Step 1: The UE accesses a base station via access Petition 870250104104, dated 11 / 13 / 2025, page 42 / 102 36 / 81 random (for example, the EU sends a preamble to a gNB-DU).

[118] Step 2: gNB-DU allocates a new cell-radio network temporary identifier (C-RNTI) for the accessed UE and sends a random access response (RAR) message to the UE.

[119] Step 3: The UE sends an RRC Reestablishment Request message to gNB-DU, in which the message includes an original UE C-RNTI and a physical cell identifier (PCI).

[120] Step 4: The gNB-DU sends an INITIAL UL RRC MESSAGE TRANSFER message to a gNB-CU, where the INITIAL UL RRC MESSAGE TRANSFER message includes the RRCReestablishmentRequest message sent by the UE, a lower layer configuration determined by the gNB-DU, and a new C-RNTI allocated by the gNB-DU.

[121] Step 5: The gNB-CU generates an RRC connection reestablishment message, and sends the RRC connection reestablishment message to the gNB-DU using an RRC DL MESSAGE TRANSFER message. If the UE accesses an original gNB-DU (i.e., a gNB-DU accessed when the UE establishes an RRC connection), the gNB-CU sends an old UE F1AP ID from the gNB-DU to the gNB-DU (e.g., the UE in Figure 6A and Figure 6B performs the RRC connection reestablishment on the original gNB-DU, i.e., the RRC connection establishment and the RRC connection reestablishment are performed on the same gNB-DU).

[122] Step 6: gNB-DU obtains UE context information based on the old gNB-DU UE F1AP ID (for example, UE context information may include a UE-related configuration maintained by gNB-DU) and updates an original UE C-RNTI / PCI. Petition 870250104104, dated 11 / 13 / 2025, page 43 / 102 37 / 81 for a new C-RNTI / PCI.

[123] Step 7: The UE sends an RRCReestablishmentComplete message to gNB-DU.

[124] Step 8: gNB-DU transmits an RRC message from UE to gNB-CU using a DL RRC MESSAGE TRANSFER message.

[125] Step 9: The gNB-CU triggers a UE context modification procedure, for example, it sends a UE CONTEXT MODIFICATION REQUEST message to the gNB-DU, in which the message includes radio carrier establishment indication information.

[126] Step 10: gNB-DU sends a UE CONTEXT MODIFICATION RESPONSE message to gNB-CU.

[127] Steps 9 and 10 are optional. For example, UE context information cannot be modified, i.e., the procedure in Figure 6A and Figure 6B does not include steps 9 and 10. Optionally, the gNB-DU triggers the UE context modification procedure. In this case, the sender and receiver of the message in steps 9 and 10 are swapped (e.g., steps 9' and 10' in Figure 6B). Optionally, if the UE accesses the base station using a new gNB-DU, UE context re-establishment will need to be performed.

[128] Step 11: The gNB-CU generates an RRC reconfiguration message from the UE and sends the RRCReconfiguration message to the gNB-DU.

[129] Step 12: gNB-DU sends the RRCReconfiguration message to UE.

[130] Step 13: The UE sends an RRC reconfiguration completed message (RRCReconfigurationComplete) to the gNB-DU, to indicate that the configuration has been completed. Petition 870250104104, dated 11 / 13 / 2025, page 44 / 102 38 / 81

[131] Step 14: gNB-DU sends the RRCReconfigurationComplete message to gNB-CU. II. Communication method provided in this request

[132] Figure 7 is a schematic flowchart of a communication method according to this request. The communication method can be applied to the communication system shown in Figure 1. For example, the communication method can be implemented through the interaction between a first network device (e.g., a DU) and a second network device (e.g., a CU). The communication method includes the following steps.

[133] S101: The second network device sends indication information to the first network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier and, correspondingly, the first network device receives the indication information from the second network device.

[134] S102: The second network device sends a first message to the first network device, where the first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection.

[135] The first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit the first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between a second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device.

[136] For example, in the communication system shown in Figure 1, the first terminal device may be a remote UE, Petition 870250104104, dated 11 / 13 / 2025, page 45 / 102 39 / 81 The second terminal device can be a relay UE, the first network device is a DU (the DU is used as an example for description in this application), and the second network device is a CU (the CU is used as an example for description in this application). For example, the first connection is an RRC connection between the remote UE and a gNB-CU, and correspondingly, the first message is an RRC connection restoration message, an RRC connection resumption message, or an RRC connection release message. For example, the first carrier is an SRB signaling radio carrier from the remote UE and is used to transmit an RRC connection restoration message, an RRC connection resumption message, or an RRC connection release message between the remote UE and the gNB-CU.The second carrier is a Uu retransmission RLC channel and is used to transmit an RRC reconnection message, an RRC reconnection message, or an RRC reconnection release message between the retransmission UE and a gNB-DU. The first carrier can be multiplexed onto the second carrier, i.e., a remote UE SRB can be multiplexed onto the Uu retransmission RLC channel. The gNB-CU can perform SRAP configuration on the retransmission UE. The SRAP configuration includes the first mapping link between the first carrier and the second carrier, and the first mapping link can be a mapping link (also called a mapping link configuration) between the remote UE SRB and the Uu retransmission RLC channel. Optionally, the gNB-DU also needs to obtain the first mapping link so that the gNB-DU transmits the first message to the retransmission UE based on the first mapping link.

[137] For example, if the indication information sent by the second network device to the first network device is used to determine the first mapping relationship between the first carrier and the second carrier, Petition 870250104104, dated 11 / 13 / 2025, page 46 / 102 40 / 81 before sending the RRC reconnection message or the RRC reconnection message, the first network device can determine a mapping relationship that is between the remote UE's SRB and the Uu relay RLC channel and that is used to send the RRC reconnection message or the RRC reconnection message, so that the remote UE completes an RRC reconnection / RRC reconnection procedure using the relay UE.

[138] Specifically, the first message is the first downlink message sent by the second network device to the first terminal device in the procedure to re-establish or resume the first connection and may include, but is not limited to, the following messages.

[139] (1) The first message is an RRC connection restoration message.

[140] For example, in an RRC connection restoration procedure, the gNB-CU generates an RRC connection restoration message, and transmits the RRC connection restoration message to the remote UE via the gNB-DU and the relay UE. In this scenario, the first message can also be called the first downlink SRB1 message in the RRC connection restoration procedure. The first mapping relationship is a mapping relationship between an SRB1 and the Uu relay RLC channel. In this example, the first downlink message is a downlink SRB1 message sent by a CU to a DU.

[141] (2) The first message is an RRC connection resumption message.

[142] For example, in an RRC reconnection procedure (the RRC reconnection procedure is used by the UE to enter a connected state from a non-connected state (RRC_INACTIVE)), the gNB-CU generates a message of Petition 870250104104, dated 11 / 13 / 2025, page 47 / 102 41 / 81 RRC connection resumption, and transmits the RRC connection resumption message to the remote UE via the gNB-DU and the relay UE. In this scenario, the first message can also be called the first downlink SRB1 message in the RRC connection resumption procedure. The first mapping relationship is a mapping relationship between an SRB1 and the Uu relay RLC channel. In this example, the first downlink message is a downlink SRB1 message sent by a CU to a DU.

[143] (3) The first message is an RRC connection release message.

[144] For example, in an RRC connection resumption procedure, if the gNB-CU indicates that the first terminal device should return to a disconnected state or enter an idle state (e.g., instructing the UE to release an RRC connection or suspend an RRC connection), the gNB-CU may generate an RRC connection release message (RRCrelease with suspension or RRCrelease). Furthermore, the gNB-DU and the relay UE transmit the RRC connection release message to the remote UE. In this scenario, the first message may also be called the first downlink SRB1 message in the RRC connection resumption procedure. The first mapping relationship is a mapping relationship between an SRB1 and the Uu relay RLC channel. In this example, the first downlink message is a downlink SRB1 message sent by a CU to a DU.

[145] (4) The first message is an RRC configuration message.

[146] For example, in an RRC reconnection or reconnection procedure, if the gNB-CU cannot find UE context information from the remote UE (for example, the gNBCU performs the determination and the gNB-CU cannot determine the UE context information from the remote UE and cannot indicate Petition 870250104104, dated 11 / 13 / 2025, page 48 / 102 42 / 81 a gNB-DU to obtain the UE context from the remote UE), the gNB-CU generates and sends an RRC setup message, and transmits the RRC setup message to the remote UE using the relay UE. In this scenario, the first message can also be called the first downlink SRB0 message in the RRC reconnection or connection recovery procedure. Optionally, the gNB-CU needs to determine a mapping relationship between an SRB0 and the Uu relay RLC channel and send the mapping relationship between an SRB0 and the Uu relay RLC channel to the gNB-DU. In this example, the first downlink message is a downlink SRB0 message sent by a CU to a DU.

[147] (5) The first message is an RRC rejection message.

[148] For example, in an RRC connection resumption procedure, if the gNB-CU rejects the RRC connection resumption from the remote UE, the gNB-CU may send an RRC rejection message (RRCreject) to the remote UE. In this scenario, the first message may also be called the first downlink SRB0 message in the RRC connection resumption procedure. Optionally, the gNB-CU needs to determine a mapping relationship between an SRB0 and the Uu retransmission RLC channel and send the mapping relationship between an SRB0 and the Uu retransmission RLC channel to the gNB-DU. In this example, the first downlink message is a downlink SRB0 message sent by a CU to a DU.

[149] Optionally, for (1), (2), (3) and (5), it can be determined whether the first mapping relationship in the UE context information of the remote UE is used or whether the first mapping relationship is redetermined based on a relay UE status.

[150] Optionally, there may be an implementation sequence for S101 and S102. For example, S101 is performed before Petition 870250104104, dated 11 / 13 / 2025, page 49 / 102 43 / 81 of S102. Alternatively, S101 and S102 can be performed simultaneously. For example, the second network device simultaneously sends the indication information and the first message. Alternatively, S102 can be performed before S101. In this case, after receiving the first message, the first network device determines the first mapping relationship after the second network device sends the indication information and transmits the first message based on the first mapping relationship. Specific implementations are not limited in this application.

[151] S103: The first network device transmits the first message based on the first mapping relationship.

[152] For example, gNB-DU sends the RRC connection restoration message, the RRC connection resumption message, the RRC connection release message, the RRC configuration message, or the RRC rejection message to the relay UE via a corresponding Uu relay RLC channel based on the mapping relationship between the remote UE SRB and the Uu relay RLC channel.

[153] It can be understood that the previous examples do not limit the solutions to this request.

[154] In this mode, before sending the first message, the second network device can send the indication information to the first network device, so that the first network device can determine, based on the indication information, a configuration of the first mapping relationship used to transmit the first message, in order to correctly transmit the first message. In this way, the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station.

[155] 3. If the second network device does not update the Petition 870250104104, dated 11 / 13 / 2025, pp. 50 / 102 44 / 81 first mapping relationship, a specific implementation of the communication method provided in this application is as follows.

[156] Specifically, in this mode, the second network device can apply an original SRAP configuration in the context of UE (i.e., an SRAP configuration used before the re-establishment or resumption procedure of the first connection). The SRAP configuration includes the first mapping relationship between the first carrier and the second carrier.

[157] For example, Figure 8 is a schematic flowchart of another communication method in accordance with this request. The method includes the following steps.

[158] S201: The second network device determines to apply an adaptation layer configuration before a procedure to re-establish or resume a first connection.

[159] Optionally, the second network device may determine, based on a second message and information corresponding to the second terminal device, that the second terminal device is a relay terminal device associated with the first terminal device before the first connection re-establishment or resumption procedure. In this case, the second network device determines to apply the adaptation layer configuration before the first connection re-establishment or resumption procedure. For example, the second message is an SRB0 message, and the SRB0 message includes an RRC connection re-establishment or resumption request message sent by the remote UE. Optionally, the SRB0 message also includes information about the remote UE, for example, an I-RNTI / CRNTI of the remote UE.The information corresponding to the second terminal device includes, for example, a second identifier (e.g., a UE gNB-DU F1AP relay ID) of the second terminal device, service information of the second terminal device (e.g., information. Petition 870250104104, dated 11 / 13 / 2025, pp. 51 / 102 45 / 81 historical relay UE service data) and context information from the second terminal device (e.g., relay UE context information). For example, gNB-DU sends the SRB0 message and the relay UE's F1AP ID gNB-DU to gNB-CU using an F1AP message. If gNB-CU determines, based on the relay UE's F1AP ID gNB-DU and the remote UE's I-RNTI / C-RNTI in the SRB0 message, that the remote UE is performing RRC connection re-establishment or RRC resumption using an original relay UE, the original SRAP configuration can be applied. The original relay UE is a relay terminal device that provides a relay service to the remote UE prior to the RRC connection re-establishment or resumption procedure.

[160] S202: The second network device sends the first indication information to the first network device, wherein the first indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an F1 interface between the first network device and the second network device.

[161] For example, the first identifier of the first terminal device is an old gNB-DU UE F1AP ID from the remote UE (i.e., an F1AP ID allocated by an original gNB-DU to the remote UE before the remote UE's RRC reconnection or re-establishment procedure), and the old gNB-DU UE F1AP ID is used in the RRC reconnection or re-establishment procedure, instructing the original gNB-DU to retrieve UE context information from the remote UE. The UE context information includes an original SRAP configuration, and the SRAP configuration includes the first mapping relationship between the first carrier and the second carrier. For example, the first mapping relationship Petition 870250104104, dated 11 / 13 / 2025, pp. 52 / 102 46 / 81 includes a mapping relationship between an SRB1 (used to carry an RRC reconnection message, an RRC reconnection message, or an RRC reconnection message) from the remote UE and a Uu relay RLC channel. For another example, the first mapping relationship includes a mapping relationship between an SRB0 (used to carry an RRC configuration message or an RRC rejection message) from the remote UE and the Uu relay RLC channel.

[162] S203: The first network device obtains context information from the first terminal device based on the first identifier.

[163] For example, gNB-DU looks up UE context information from the remote UE based on the old gNB-DU UE F1AP ID of the remote UE, where the UE context information includes a mapping relationship originally configured between a radio carrier of the remote UE and the Uu relay RLC channel.

[164] S204: The first network device determines the first mapping relationship based on context information from the first terminal device.

[165] In a possible implementation, S204 specifically includes the following procedure.

[166] The first network device determines the first mapping relationship based on the second indication information and the context information of the first terminal device, where the second indication information indicates the first network device to apply the first mapping relationship.

[167] For example, gNB-CU may indicate, based on the second indication information, that gNB-DU should apply the first mapping relationship originally configured. In this case, gNB-DU may determine, based on the UE context information found from the remote UE, to apply the relationship of Petition 870250104104, dated 11 / 13 / 2025, page 53 / 102 47 / 81 mapping originally configured between the remote UE radio carrier and the Uu relay RLC channel, included in the UE context information.

[168] Optionally, when gNB-DU searches for UE context and actively releases the mapping relationship between the remote UE radio carrier and the Uu relay RLC channel by default, gNB-CU can instruct gNB-DU to maintain the originally configured mapping relationship between the remote UE radio carrier and the Uu relay RLC channel. In this case, gNB-DU can determine, based on the UE context information found on the remote UE, whether to apply the originally configured mapping relationship between the remote UE radio carrier and the Uu relay RLC channel.

[169] Optionally, if gNB-CU indicates to gNB-DU not to release an originally configured SRAP configuration (for example, additionally sending 1-bit indication information to indicate not to release the SRAP configuration), gNB-DU may determine, based on the UE context information found from the remote UE, to apply the originally configured mapping relationship between the remote UE radio carrier and the Uu relay RLC channel.

[170] In another possible implementation, S204 specifically includes the following procedure.

[171] The first network device determines the first mapping relationship based on the first identifier of the first terminal device, the context information of the first terminal device and the corresponding information of the second terminal device.

[172] For example, gNB-DU can determine, based on the old gNB-DU UE F1AP ID of the remote UE and the corresponding relay UE information (e.g., including the second identifier (e.g., the relay UE F1AP ID) of the second terminal device, the information Petition 870250104104, dated 11 / 13 / 2025, pp. 54 / 102 48 / 81 service information from the second terminal device (e.g., historical service information from the relay UE) and the context information from the second terminal device (e.g., context information from the relay UE), which the remote UE accesses from an original relay UE. Therefore, the first mapping relationship configured in the context of the first terminal device's UE can be applied. gNB-DU determines, based on the context information found from the remote UE, that the first mapping relationship is the mapping relationship originally configured between the remote UE's radio carrier and the relay Uu's RLC channel.

[173] Optionally, if gNB-DU finds that gNB-CU does not set up a mapping relationship and a mapping relationship in the context of the remote UE is not available, for example, gNB-DU determines that the remote UE performs access via the new relay UE, gNB-DU may still request that gNB-CU indicate the first mapping relationship.

[174] Optionally, the first network device may determine, based on the first identifier of the first terminal device and the corresponding information of the second terminal device, the release of a second mapping relationship. The second mapping relationship is included in the context information of the first terminal device, and the first mapping relationship is different from the second mapping relationship. For example, it is assumed that, prior to the RRC reconnection or connection resumption procedure, the context information of the first terminal device includes a mapping relationship between the radio carrier of the remote UE and the Uu relay RLC channel (e.g., it includes a mapping relationship between an SRB0 / SRB1 / SRB2 and the Uu relay RLC channel). The first mapping relationship includes the mapping relationship between SRB1 and the RLC channel of Petition 870250104104, dated 11 / 13 / 2025, page 55 / 102 49 / 81 Uu retransmission, and the second mapping relationship includes the mapping relationship between SRB0 / SRB2 and the Uu retransmission RLC channel. gNB-DU can determine, based on the old gNB-DU UE F1AP ID of the remote UE and the corresponding information for the retransmission UE, that the remote UE performs access from the original retransmission UE and can release the mapping relationship between SRB0 / SRB2 and the Uu retransmission RLC channel.

[175] Optionally, the first network device receives third indication information from the second network device, wherein the third indication information indicates that the first network device should release the second mapping link. For example, gNB-CU may additionally send 1-bit indication information to gNB-DU to indicate the release of the mapping link between SRB0 / SRB2 and the Uu relay RLC channel.

[176] S205: The second network device sends a first message to the first network device, the first message being a first downlink message sent by the second network device to the first terminal device in the procedure for re-establishing or resuming the first connection. For example, the first message is an RRC connection re-establishment message, an RRC connection resumption message, an RRC connection release message, or an RRC rejection message. For specific descriptions of the first message and a specific implementation of S205, see the descriptions of the first message (including the descriptions of (1), (2), (3), and (5) of the first downlink message) and the procedure in which the second network device sends the first message to the first network device in S102. Details are not described again in this document.

[177] S206: The first network device transmits the first message based on the first mapping relationship.

[178] For a specific implementation of S206, see Petition 870250104104, dated 11 / 13 / 2025, pp. 56 / 102 50 / 81 corresponding description in S103. Details are not described again in this document.

[179] Optionally, there may be a sequence of implementation of S202 and S205. For example, S202 is performed before S205. Alternatively, S202 and S205 may be performed simultaneously. For example, the second network device simultaneously sends the indication information and the first message. Alternatively, S205 may be performed before S202. In this case, after receiving the first message, the first network device determines the first mapping relationship after the second network device sends the indication information and transmits the first message based on the first mapping relationship. Specific implementations are not limited in this application.

[180] In this mode, when the first terminal device re-establishes or resumes the first connection through the second terminal device, if the second network device does not update the first mapping relationship and the first network device has a first mapping relationship available, the second network device can instruct the first network device to forward the first message using the first mapping relationship in the original UE context information. In this way, the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station. Optionally, when the first message is the RRC configuration message or the RRC rejection message, the first network device can correctly send a first downlink SRB message.

[181] 4. If the second network device updates the first mapping relationship, a specific implementation of the communication method provided in this application will be as follows.

[182] Specifically, in this modality, the second Petition 870250104104, dated 11 / 13 / 2025, pp. 57 / 102 Network devices 51 / 81 can update the SRAP configuration. The SRAP configuration includes the first mapping relationship between the first carrier and the second carrier. In other words, the second network device updates the first mapping relationship.

[183] ​​For example, Figure 9 is a schematic flowchart of another communication method in accordance with this request. The method includes the following steps.

[184] S301: A second network device determines to update a first mapping relationship.

[185] In one possible implementation, when the remote UE re-establishes or resumes an RRC connection via the original relay UE, the second network device may update a first mapping relationship using the first mapping relationship originally configured (e.g., S201), or it may not update the first mapping relationship using the first mapping relationship originally configured. For example, the second network device resets the mapping relationship between the remote UE's SRB1 and the relay RLC channel of Uu.

[186] In another possible implementation, when the remote UE re-establishes or resumes an RRC connection via a new relay UE, the second network device determines the update of the first mapping relationship. Optionally, the second network device determines, based on the first identifier of the first terminal device, the context information of the first terminal device, and the corresponding information of the second terminal device, the update of the first mapping relationship. A relay terminal device associated with the second terminal device is different from a relay terminal device associated with the first terminal device before a procedure to re-establish or resume a first connection. The Petition 870250104104, dated 11 / 13 / 2025, pp. 58 / 102 52 / 81 The relay terminal device associated with the second terminal device is different from the relay terminal device associated with the first terminal device before the re-establishment or resumption of the first connection procedure. In other words, the relay UE is a new relay UE.

[187] For example, the second message is an SRB0 message, and the SRB0 message includes a request to restore or resume RRC connection sent by the remote UE. Optionally, the SRB0 also includes information about the remote UE, for example, an I-RNTI / C-RNTI of the remote UE. For example, the information corresponding to the second terminal device includes a new UE F1AP relay ID, and the new UE F1AP relay ID can be carried in an INITIAL UL RRC message. For example, a gNB-DU sends the SRB0 message and the new UE F1AP relay ID to a gNB-DU using the INITIAL UL RRC message.

[188] In this case, gNB-CU can redefine a mapping relationship between the remote UE's SRB1 and a new Uu relay RLC channel (based on the new relay UE).

[189] Optionally, when the remote UE re-establishes or resumes an RRC connection via the new relay UE, the new relay UE can be connected to a new first network device. In this case, the second network device can further reconfigure the first mapping relationship to the first network device. For example, the second network device sends the mapping relationship between the remote UE's SRB1 and the new Uu relay RLC channel (based on the new relay UE) to the first network device.

[190] S302: The second network device sends indication information to the first network device, where the indication information includes the first mapping relationship. Petition 870250104104, dated 11 / 13 / 2025, pp. 59 / 102 53 / 81

[191] It can be understood that the first mapping relationship is an updated first mapping relationship. For example, gNB-CU can directly send the mapping relationship between the remote UE SRB1 and the new Uu relay RLC channel to gNB-DU.

[192] Optionally, the first network device may determine, based on the first identifier of the first terminal device and the corresponding information of the second terminal device, the release of a second mapping link. For example, if the gNB-DU determines that the remote UE should re-establish or resume the RRC connection via the new relay UE, the gNB-DU determines the release of a mapping link between an SRB0 / SRB2 in the context information of the first terminal device and an original Uu relay RLC channel. Optionally, the first network device receives third indication information from the second network device, wherein the third indication information indicates that the first network device should release the second mapping link.For example, gNB-CU can additionally send 1-bit indication information to gNB-DU to indicate the release of the mapping link between SRB0 / SRB2 in the context information of the first terminal device and the original Uu relay RLC channel.

[193] S303: The second network device sends a first message to the first network device, the first message being a first downlink message sent by the second network device to the first terminal device in the procedure of re-establishing or resuming the first connection. For example, the first message is an RRC connection re-establishment message, an RRC connection resumption message, an RRC connection release message, an RRC configuration message, or a rejection message. Petition 870250104104, dated 11 / 13 / 2025, pages 60 / 102 54 / 81 RRC. For specific descriptions of the first message and a specific implementation of S303, see the descriptions of the first message (including descriptions (1) to (5) of the first downlink message) and the procedure in which the second network device sends the first message to the first network device in S102. Details are not described again in this document.

[194] S304: The first network device transmits the first message based on the first mapping relationship.

[195] For a specific implementation of S304, see the corresponding description in S103. Details are not described again in this document.

[196] Optionally, there may be a sequence of implementation of S302 and S303. For example, S302 is performed before S303. Alternatively, S302 and S303 may be performed simultaneously. For example, the second network device simultaneously sends the indication information and the first message. Alternatively, S303 may be performed before S302. In this case, after receiving the first message, the first network device determines the first mapping relationship after the second network device sends the indication information and transmits the first message based on the first mapping relationship. This is not limited in this application.

[197] In this mode, if the second network device updates the first mapping relationship, the second network device can directly send the updated first mapping relationship to the first network device, so that the first network device transmits the first message based on the updated first mapping relationship. In this way, the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station.

[198] Detailed descriptions are provided below of Petition 870250104104, dated 11 / 13 / 2025, pp. 61 / 102 55 / 81 when the communication methods described in parts two through four are applied to an RRC connection restoration procedure in the CU-DU split architecture.

[199] 5. It is assumed that, regardless of whether the second network device updates the first mapping relationship or not, the originally configured SRAP configuration will not be released. The specific implementation of the communication method provided in this application is as follows.

[200] Figures 10A to 10C represent a schematic flowchart of yet another communication method, according to this application. The procedure includes an operational procedure in which a first terminal device (remote UE) re-establishes an RRC connection via a second terminal device (relay UE) and a base station (including a gNB-CU and a gNB-DU) configures an SL relay for the remote UE in the split CU-DU architecture.

[201] Step 1: The remote UE searches for the appropriate relay UE using a discovery procedure on a side link and establishes a unicast connection with the selected relay UE.

[202] Step 2: The remote UE sends an RRC reconnection request message to the relay UE via a PC5 relay RLC channel corresponding to an SRB (e.g., an SRB0), to request that the relay UE forward the RRC reconnection request message to a first network device.

[203] Step 3: The relay UE sends a SUI message to the base station, where the SUI message carries an L2 ID identifier from the remote UE.

[204] Step 4: gNB-DU sends gNB-CU an uplink RRC message (UL RRC MESSAGE TRANSFER message) carrying the SUI message. After Petition 870250104104, dated 11 / 13 / 2025, pages 62 / 102 56 / 81 receiving the message, the gNB-CU allocates a local ID to the remote UE and configures the relay UE to provide a relay for the remote UE.

[205] Step 5 / 6: Performs a UE CONTEXT MODIFICATION procedure from the relay UE to generate a relay configuration on a relay UE side. Specifically, gNB-CU sends a UE CONTEXT MODIFICATION REQUEST message to gNB-DU to request the establishment of a Uu relay RLC channel. The Uu relay RLC channel is used to carry an SRB0 message from the remote UE (optionally, the Uu relay RLC channel used to carry an SRB1 may be included). gNB-DU sends a UE CONTEXT MODIFICATION RESPONSE message to gNB-CU to provide a Uu relay RLC channel configuration required by gNB-CU.

[206] Step 7 / 8: The gNB-CU generates an RRC configuration (RRCReconfiguration) on the relay UE side and sends the RRC configuration to the relay UE via the gNBDU. For example, the gNB-CU sends a downlink RRC message transfer (UL RRC MESSAGE TRANSFER) to the gNBDU, where the message carries the RRC configuration on the relay UE side. The gNB-DU sends the RRC configuration on the relay UE side to the relay UE.

[207] Step 9 / 10: The relay UE sends the RRC configuration completion to the gNB-CU. For example, the relay UE sends an RRC configuration completion message (RRCReconfigurationComplete) to the gNB-DU, and the gNB-DU sends an uplink RRC transfer message (DL RRC MESSAGE TRANSFER) to the gNB-CU, where the message carries the RRCReconfigurationComplete.

[208] Step 11: The relay UE sends a message of Petition 870250104104, dated 11 / 13 / 2025, pp. 63 / 102 57 / 81 Request for re-establishment of RRC connection from the remote UE to gNB-DU based on a base station configuration (including the local ID of the remote UE, a Uu relay RLC channel configuration, and a mapping relationship between at least one SRB0 and the Uu relay RLC channel).

[209] Step 12: The gNB-DU adds the remote UE's RRC connection restoration request message to an initial uplink RRC message (INITIAL UL RRC MESSAGE TRANSFER message) and sends the message to the gNB-CU. Additionally, the message includes a relay UE F1AP ID and the local ID of the remote UE, to indicate to the gNB-CU that the remote UE is associated with the relay UE. In step 4, the local ID is allocated by the gNB-CU. The message may also include a PC5 relay RLC channel configuration corresponding to an SRB1 message from the remote UE.

[210] Steps 1 through 12 include, but are not limited to, the following cases.

[211] Case 1: The remote UE accesses an original gNB-DU via an original relay UE and performs RRC connection re-establishment.

[212] In Case 1, when the remote UE requests, through the original relay UE, the re-establishment of an RRC connection, the remote UE may not release a previously established side link connection with the original relay UE. Therefore, step 1 may not be performed in Case 1. Furthermore, the remote UE performs the re-establishment through the original relay UE. Therefore, a remote UE relay forwarding configuration is configured on the original relay UE side. Thus, upon receiving the RRC connection re-establishment request message from the remote UE, the original relay UE directly forwards the RRC connection re-establishment request message based on an SRB0 mapping relationship configuration. Petition 870250104104, dated 11 / 13 / 2025, pp. 64 / 102 58 / 81 original (including a mapping relationship between an SRB0 and the Uu relay RLC channel) (steps 3 to 10 can be skipped and step 11 is performed directly). In other words, in step 11, the relay UE sends the RRC connection restoration request message from the remote UE to the original gNB-DU based on the original mapping relationship between the SRB0 and the Uu relay RLC channel.

[213] In step 12, the original gNB-DU includes SRB0 in an INITIAL UL RRC MESSAGE TRANSFER message and forwards the message to the gNB-CU. Additionally, the message includes an original relay F1AP UE ID and a local ID of the remote UE. The local ID of the remote UE is a local ID added to an adaptation layer header when the relay UE forwards the SRB0 message. Based on step 12, the gNB-CU determines that the remote UE re-establishes an RRC connection through the original relay UE (similar to S201).

[214] Case 2: The remote UE accesses the original gNB-DU via the new relay UE, and performs RRC connection re-establishment.

[215] In Case 2, when the remote UE accesses the original gNB-DU via the new relay UE, a Uu relay RLC channel (considered a new Uu relay RLC channel) between the new relay UE and the original gNBDU is used to port data from the remote UE to the Uu. Therefore, a mapping relationship between the relay UE side and the gNB-DU side needs to be reconfigured. In other words, steps 1 to 12 need to be performed sequentially in Case 2. For example, in steps 5 / 6, a new relay configuration on the relay UE side needs to be generated (including the generation of a mapping relationship between SRB0 / SRB1 and the new Uu relay RLC channel). In steps 7 / 8, a new RRC configuration on the relay UE side needs to be generated, and so on. Petition 870250104104, dated 11 / 13 / 2025, pages 65 / 102 59 / 81 onwards. For a specific implementation, refer to the descriptions in a protocol standard. Details are not described again in this document.

[216] In step 12, gNB-DU adds the remote UE's RRC connection restoration request message, a gNB-DU UE F1AP ID of the new relay UE, and the local ID of the remote UE to the INITIAL UL RRC MESSAGE TRANSFER message. gNB-CU determines, based on the information carried in the RRC message sent by the remote UE and the relay UE F1AP ID information, that the remote UE performs the RRC connection restoration via the new relay UE and determines that the SRAP mapping relationship configuration needs to be updated (similar to S301).

[217] Case 3: The remote UE accesses a new gNB-DU via the new relay UE, and performs RRC connection re-establishment.

[218] In Case 3, when the remote UE accesses the new gNB-DU via the new relay UE, since the new gNB-DU cannot directly obtain the UE context from the remote UE, the gNB-CU needs to reset the SRAP mapping relationship settings on the relay UE side and on the gNB-DU side.

[219] For example, in step 12, the gNB-CU determines, based on the remote UE information carried in the RRC restoration request message and the new UE F1AP relay ID indicated by the gNB-DU, and determines that the remote UE perform RRC restoration via a new gNB-DU (similar to the optional descriptions in S301).

[220] Step 13: On the relay UE side, the gNB-CU configures the PC5 relay RLC channel and the Uu relay RLC channel for relaying and forwarding the SRB1 message from the remote UE, and a mapping relationship between SRB1 and the PC5 / Uu relay RLC channel. Additionally, the gNB-CU sends the above configuration to the UE of Petition 870250104104, dated 11 / 13 / 2025, pp. 66 / 102 60 / 81 retransmission via gNB-DU, to transmit an SRB1 message (e.g., including an RRC reconnection message and an RRC reconnection completed message).

[221] Step 14 / 15: The gNB-CU generates an RRC re-establishment message from the remote UE, and transmits the RRC re-establishment message to the remote UE via the gNB-DU and the relay UE. For example, the gNB-CU sends a downlink RRC transfer message (UL RRC MESSAGE TRANSFER) to the gNB-DU, and the gNB-DU transmits an RRC re-establishment message (RRCReestablishment) to the remote UE via the relay UE.

[222] In steps 13 to 15, from Case 1 to Case 3 there are also different implementations, including the following.

[223] For Case 1: In step 13, since both the relay UE and the gNBDU are original devices, the gNB-CU does not need to reconfigure the mapping relationship between SRB1 and the PC5 / Uu relay RLC channel on the relay UE side. For example, in step 14, the gNB-CU generates an RRC reconnection message from the remote UE, appends the RRC reconnection message to a DL RRC MESSAGE TRANSFER message, and sends the DL RRC MESSAGE TRANSFER message to the gNB-DU. Optionally, if the procedure is an RRC reconnection procedure, in step 14, the gNB-CU generates an RRC reconnection message or an RRC connection release message from the remote UE, adds the RRC reconnection message or the RRC connection release message to an RRC DL MESSAGE TRANSFER message, and sends the RRC DL MESSAGE TRANSFER message to the gNB-DU.Optionally, in the DL RRC MESSAGE TRANSFER procedure, the... Petition 870250104104, dated 11 / 13 / 2025, pp. 67 / 102 61 / 81 RRC connection re-establishment or resumption, the gNB-CU generates and transmits the first downlink SRB0 message in step 14, and the first downlink SRB0 message may be an RRC rejection message. For specific descriptions of the preceding message, see the descriptions of the first message (including descriptions of (1), (2), (3) and (5) of the first downlink message) in S102. Details are not described again in this document.

[224] Optionally, gNB-CU can send additional indication information to gNB-DU, to indicate the old gNBDU UE F1AP ID of the remote UE. The old gNB-DU UE F1AP ID of the remote UE is used by gNB-DU to look up the UE context of the remote UE. The UE context includes the previously configured SRAP mapping relationship configuration (similar to S202 for S205).

[225] In one possible implementation, the gNB-CU determines to apply the original configuration. Therefore, the gNB-CU does not need to update an SRB1 mapping relationship (a mapping relationship between an SRB1 and a Uu relay RLC channel) on the gNB-DU side. Similarly, an original SRB1 mapping relationship is also used on the UE relay side.

[226] Optionally, in step 13, the gNB-CU updates only one PC5 relay RLC channel setting. Optionally, step 13 is not performed.

[227] Optionally, in step 14, gNB-CU does not send an SRAP mapping relationship configuration update indication to gNB-DU.

[228] Optionally, in step 14, gNB-CU sends indication information to gNB-DU, and gNB-DU can apply the SRB1 mapping relationship configuration to the UE context information based on the indication information (similar to a possible implementation described in S204).

[229] Optionally, in step 14, gNB-DU can determine, Petition 870250104104, dated 11 / 13 / 2025, pages 68 / 102 62 / 81 based on the old gNB-DU UE F1AP ID and the associated relay UE, which the remote UE performs access from the original relay UE. Therefore, an SRB1 mapping relationship configuration on the UE context information can be applied (similar to another possible implementation described in S204).

[230] Optionally, in step 14, it is assumed in this mode that, after gNB-DU searches the UE context information of the remote UE based on the old gNB-DU UE F1AP ID indicated by gNB-CU, the SRAP configuration in the UE context information is not released by default, gNB-CU can indicate to gNB-DU to retain the mapping relationship configuration of SRB1 or indicate configurations that can be retained (e.g., indicate to retain a mapping relationship configuration of SRB0).

[231] Optionally, in step 15, gNB-DU sends the RRC connection restoration message from the remote UE to the relay UE based on the SRB1 mapping relationship configuration in the UE context information.

[232] In another possible implementation, the gNB-CU determines the update of the SRB1 mapping relationship (the mapping relationship between SRB1 and the Uu retransmission RLC channel). Therefore, in step 13, the gNB-CU determines a new mapping relationship between SRB1 and the Uu retransmission RLC channel and updates the SRB1 mapping relationship on the UE retransmission side.

[233] Optionally, in step 14, gNB-CU sends indication information to gNB-DU, to indicate to gNB-DU to update the SRAP mapping relationship configuration. The indication information includes a new mapping relationship between SRB1 and the Uu relay RLC channel (similar to S301 and S302).

[234] Optionally, in step 15, the gNB-DU transmits the RRC connection restoration message to the remote UE via the relay UE based on the new relationship. Petition 870250104104, dated 11 / 13 / 2025, pp. 69 / 102 63 / 81 mapping that exists between SRB1 and the Uu retransmission RLC channel and that is indicated by gNB-CU.

[235] For Case 2: In step 13, gNB-CU updates the SRB1 mapping relationship configuration on the UE relay side, including updating a mapping relationship between SRB1 and the Uu relay RLC channel and a mapping relationship between SRB1 and the PC5 relay RLC channel.

[236] In step 14, gNB-CU sends indication information to gNB-DU, wherein the indication information includes a new mapping relationship between SRB1 and the Uu relay RLC channel. Optionally, gNB-CU sends the old gNBDU UE F1AP ID of the remote UE to gNB-DU, so that gNB-DU can look up the UE context.

[237] Optionally, it is assumed in this embodiment that, after gNB-DU fetches UE context information based on the old gNB-DU UE F1AP ID indicated by gNB-CU, and after UE context information from the remote UE, the SRAP configuration in the UE context information is not released by default. When the mapping relationship between SRB1 and the Uu relay RLC channel and the mapping relationship between SRB1 and the PC5 relay RLC channel are updated, gNB-CU may still instruct gNB-DU to release all SRAP mapping relationship settings (e.g., including an original mapping relationship between SRB1 / SRB0 and the Uu relay RLC channel) obtained by fetching the UE context, and apply a newly configured SRB1 mapping relationship setting.Alternatively, gNB-DU determines, based on the old gNB-DU UE F1AP ID indicated by gNB-CU and the relay UE associated with the UE, that the remote UE accesses the base station via the new relay UE and autonomously releases the SRAP mapping relationship configuration obtained by fetching the UE context information. Petition 870250104104, dated 11 / 13 / 2025, pp. 70 / 102 64 / 81

[238] For example, in step 15, gNB-DU transmits the RRC reconnection message to the remote UE via the relay UE based on the new mapping relationship between SRB1 and the Uu relay RLC channel. Optionally, if an RRC reconnection procedure is performed, in step 15, gNB-DU transmits the RRC reconnection message or the RRC connection release message to the remote UE via the relay UE based on the new mapping relationship between SRB1 and the Uu relay RLC channel. Optionally, in the RRC reconnection or reconnection procedure, gNB-DU transmits the first downlink SRB0 message in step 15, and the first downlink SRB0 message may be an RRC rejection message.For specific descriptions of the previous message, see the descriptions of the first message (including descriptions of (1), (2), (3) and (5) of the first downlink message) in S102. Details are not described again in this document.

[239] For Case 3: In step 13, gNB-CU determines a new SRB1 mapping relationship configuration (including a new mapping relationship between SRB1 and the Uu retransmission RLC channel) and updates the SRB1 mapping relationship on the UE retransmission side.

[240] In step 14, gNB-CU sends a new mapping relationship between SRB1 and the Uu relay RLC channel to gNB-DU.

[241] Optionally, if the gNB-CU determines, based on the message received in step 12, that the remote UE re-establishes the RRC connection via a new gNB-DU, the gNB-CU needs to determine and port a new mapping relationship between SRB0 and the Uu relay RLC channel in step 14.

[242] For example, in step 15, gNB-DU transmits the message Petition 870250104104, dated 11 / 13 / 2025, pp. 71 / 102 65 / 81 of RRC connection re-establishment to the remote UE via the relay UE based on the new mapping relationship between SRB1 and the Uu relay RLC channel. Optionally, if an RRC connection re-establishment procedure is performed, in step 15, gNB-DU transmits the RRC connection re-establishment message or the RRC connection release message to the remote UE via the relay UE based on the new mapping relationship between SRB1 and the Uu relay RLC channel. Optionally, in the RRC connection re-establishment or re-establishment procedure, gNB-DU transmits the first downlink SRB0 message in step 15, and the first downlink SRB0 message may be an RRC rejection message. For specific descriptions of the previous message, see the descriptions of the first message (including descriptions of (1), (2), (3) and (5) of the first downlink message) in S102.Details are not described again in this document.

[243] Steps 16 / 17: The remote UE transmits an RRC Reestablishment Complete message to the gNB-CU via the relay UE and the gNB-DU. For example, the remote UE transmits the RRC Reestablishment Complete message to the gNB-DU via the relay UE. The gNB-DU sends an uplink RRC connection transfer message to the gNB-CU, where the message carries the RRC Reestablishment Complete message.

[244] Step 18 / 19: The gNB-CU can trigger a remote UE context change. For example, the gNB-CU sends a UE CONTEXT MODIFICATION REQUEST message to the gNB-DU, and the gNB-DU sends a UE CONTEXT MODIFICATION RESPONSE message to the gNB-CU.

[245] In steps 18 and 19, from Case 1 to Case 3 there is also Petition 870250104104, dated 11 / 13 / 2025, pp. 72 / 102 66 / 81 different implementations, including the following.

[246] For Case 1: Optionally, the gNB-CU can update an SRAP mapping relationship configuration (for example, a mapping relationship between an SRB2 / DRB and the Uu relay RLC channel) that is different from the SRB1 mapping relationship configuration. Specifically, the update can be performed in the UE context update procedure in steps 18 and 19. Optionally, the gNB-CU cannot update an SRAP mapping relationship configuration that is different from the SRB1 mapping relationship configuration and may not perform steps 18 and 19.

[247] For Case 2: Since the originally configured SRAP mapping relationship needs to be updated, steps 18 and 19 are mandatory and are used at least to update the SRAP mapping relationship configuration on the gNB-DU side.

[248] For Case 3: The gNB-CU triggers a UE CONTEXT CONFIGURATION procedure; that is, step 18 is a UE CONTEXT CONFIGURATION REQUEST procedure, to instruct the gNB-DU to establish a new SRB / DRB mapping relationship from the remote UE. Step 19 is a UE CONTEXT CONFIGURATION RESPONSE procedure and is used by the gNB-DU to provide a lower-layer configuration according to an instruction from the gNB-CU. For a specific implementation, refer to the corresponding description in the protocol standard. Details are not described again in this document.

[249] Step 20 / 21: The gNB-CU generates an RRC reconfiguration message from the remote UE, and sends the RRC reconfiguration message to the remote UE. For example, the gNB-CU sends a UL RRC Message Transfer message to the gNB-DU, where the Petition 870250104104, dated 11 / 13 / 2025, pp. 73 / 102 67 / 81 message port a RRCReconfiguration. The gNB-DU transmits the RRC reconfiguration message to the remote UE via the relay UE.

[250] Step 22 / 23: The remote UE sends an RRC reconfiguration complete message. For example, the remote UE transmits the RRC reconfiguration complete message to the gNB-DU via the relay UE. The gNB-DU sends an uplink RRC message transfer to the gNB-CU, where the message carries the RRCReconfigurationComplete.

[251] Step 24: The base station updates a relay configuration on the UE relay side and configures a Uu / PC5 relay RLC channel used to port the DRB and SRB from the remote UE and an SRAP mapping interface. For a specific implementation, refer to the corresponding description in the protocol standard. Details are not described again in this document.

[252] Optionally, in the split CU-DU architecture, a procedure in which the first terminal device resumes the RRC connection through the second terminal device is similar. For more details, see the procedure shown in Figure 10A to Figure 10C. One difference lies in the fact that the RRC connection re-establishment request message in step 2 / 11, the RRC connection re-establishment message in step 15, and the completed re-establishment message in step 16 are an RRC connection re-establishment request message (RRCResumeRequest), an RRC connection re-establishment message (RRCResume), and an RRC connection re-establishment completed message (RRCResumeComplete).

[253] Optionally, in this mode, it is assumed that the gNBCU cannot find the UE context information from the remote UE. In steps 13 to 15, the gNB-CU generates and sends an RRC configuration message and transmits the configuration message of Petition 870250104104, dated 11 / 13 / 2025, pp. 74 / 102 68 / 81 RRC to the remote UE via the relay UE. Optionally, gNB-CU needs to determine a mapping relationship between an SRB0 and the Uu relay RLC channel and send the mapping relationship between an SRB0 and the Uu relay RLC channel to gNB-DU.

[254] 6. It is assumed that regardless of whether the second network device updates the first mapping relationship, the originally configured SRAP configuration will be released. The specific implementation of the communication method provided in this request is as follows.

[255] A general procedure in this modality is similar to that in Figure 10A to Figure 10C. The following describes specifically a difference between this modality and the fifth part of the modalities.

[256] The procedure for steps 1 to 24 is the same as the procedure for steps 1 to 24 in Figure 10A to Figure 10C. The difference lies in the fact that, when gNB-DU retrieves UE context information from the remote UE, the originally configured SRAP mapping relationship configuration does not take effect directly by default, becomes unavailable, or needs to be released. In other words, in steps 13 to 15, Cases 1 to 3 also have different implementations, including the following.

[257] For Case 1: In a possible implementation, gNB-CU determines whether to apply the original configuration. However, if the originally configured SRAP mapping relationship configuration has been released, the processing methods of gNB-CU and gNB-DU include, among others, the following methods.

[258] Method 1: gNB-CU explicitly indicates to gNB-DU to apply the mapping relationship between SRB1 and the Uu relay RLC channel to the original UE context information. For example, gNB-CU sends second indication information to gNB-DU (e.g., second indication information). Petition 870250104104, dated 11 / 13 / 2025, pp. 75 / 102 69 / 81 are 1-bit indication information, similar to S204). However, gNB-DU releases a different SRAP mapping relationship configuration than the SRB1 mapping relationship. gNB-DU can transmit an RRC reconnection message, an RRC reconnection message, or an RRC reconnection release message using the mapping relationship between SRB1 and the Uu relay RLC channel in the original UE context information.

[259] Method 2: gNB-CU does not send an explicit indication to gNB-DU, but gNB-DU determines, based on the remote UE's access status, to apply the mapping relationship between SRB1 and Uu's relay RLC channel in the original UE context information. For example, gNB-DU determines, based on the old gNB-DU UE F1AP ID indicated by gNB-CU in step 14 and the relay UE associated with the remote UE, that the remote UE accesses via the original relay UE and therefore determines not to release the SRB1 mapping relationship configuration. However, gNB-DU releases a different SRAP mapping relationship configuration than the SRB1 mapping relationship. gNB-DU can transmit an RRC reconnection message, an RRC connection resumption message, or an RRC connection release message using the mapping relationship between SRB1 and the Uu retransmission RLC channel in the original UE context information.

[260] Method 3: Since gNB-DU has released all original settings, gNB-CU can directly send to gNB-DU the mapping relationship between SRB1 and the Uu relay RLC channel in the original UE context information. gNB-DU can transmit an RRC connection restoration message, an RRC connection resumption message, or an RRC connection release message using the mapping relationship between SRB1 and the Uu relay RLC channel in the original UE context information. Petition 870250104104, dated 11 / 13 / 2025, pp. 76 / 102 70 / 81

[261] In another possible implementation, gNB-CU determines the update of the SRB1 mapping relationship (the mapping relationship between SRB1 and the Uu relay RLC channel). For example, in step 14, gNB-CU directly sends a new mapping relationship between SRB1 and the Uu relay RLC channel to gNB-DU. gNB-DU can transmit an RRC reconnection message, an RRC reconnection message, or an RRC connection release message using the new mapping relationship between SRB1 and the Uu relay RLC channel.

[262] Optionally, the gNB-CU determines, based on whether the first message sent to the gNB-DU is specifically an RRC reconnection message, an RRC reconnection message, an RRC release message, an RRC configuration message, or an RRC rejection message, the sending of a mapping relationship between an SRB0 or ​​an SRB1 and a Uu relay RLC channel to the gNB-DU. For example, if the gNB-CU generates an RRC reconnection message, an RRC reconnection message, or an RRC release message from the remote UE, the gNB-CU sends the RRC reconnection message, the RRC reconnection message, or the RRC release message to the gNB-DU. In addition, the mapping relationship between SRB1 and the Uu relay RLC channel is sent to gNB-DU.Optionally, in the RRC reconnection or resumption procedure, the gNB-CU generates and transmits the first downlink SRB0 message, which may be an RRC rejection message. In this case, the gNB-CU sends the RRC configuration message or the RRC rejection message to the gNB-DU and sends the mapping relationship between SRB0 and the Uu retransmission RLC channel to the gNB-DU.

[263] For Case 2 and Case 3: Petition 870250104104, dated 11 / 13 / 2025, pp. 77 / 102 71 / 81 When the remote UE accesses an original gNB-DU via a new relay UE, or accesses a new gNB-DU via a new relay UE, a mapping relationship on the gNB-DU side needs to be reconfigured. Therefore, even if the originally configured SRAP mapping relationship is released, the mapping relationship reconfiguration is not affected. In this case, for a specific implementation in Case 2 or Case 3, refer to the corresponding descriptions in Part Five. Details are not described again in this document.

[264] To implement functions in the method provided in this application, an apparatus or device provided in this application may include a hardware structure and / or a software module, and the above functions are implemented in the form of a hardware structure, a software module, or a combination of a hardware structure and a software module. Whether a function in the above functions is performed using the hardware structure, the software module, or the combination of the hardware structure and the software module depends on specific applications and the design constraints of the technical solutions. The division into modules in this application is an example, is merely a logical division of function and may be further divided during actual implementation. Furthermore, functional modules in embodiments of this application may be integrated into a processor, or may physically exist alone, or two or more modules may be integrated into a module.The integrated module can be implemented in a hardware form, or it can be implemented in the form of a functional software module.

[265] Figure 11 is a diagram of a communication device according to this application. The device may include modules that correspond one-to-one with the methods / operations / steps / actions described in any of the embodiments shown in Figure 7 to Figure 10C. The modules may Petition 870250104104, dated 11 / 13 / 2025, pp. 78 / 102 72 / 81 can be implemented by a hardware circuit, software, or a combination of a hardware circuit and software.

[266] An 1100 device includes a communication unit 1101 and a processing unit 1102, configured to implement the methods performed by the devices in the previous embodiments.

[267] In one possible implementation, the device is an access network device (e.g., a DU) or is located on the access network device. Specifically, communication unit 1101 is configured to receive indication information from a second network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier. Communication unit 1101 is further configured to receive a first message from the second network device, wherein the first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection.The first connection is a connection between a first terminal device and a second network device. The first carrier is used to transmit the first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between the second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device. Processing unit 1102 is configured to transmit the first message based on the first mapping relationship via communication unit 1101.

[268] For specific procedures for running communication unit 1101 and processing unit 1102 in this implementation, see the descriptions of the steps performed by Petition 870250104104, dated 11 / 13 / 2025, pp. 79 / 102 73 / 81 first network device in the previous method embodiments and the corresponding descriptions in the summary. Details are not described again in this document. In the communication method implemented by the device, the access network device receives the indication information and determines, based on the indication information, the configuration of the first mapping relationship used to transmit the first message, so that the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses a corresponding access network device.

[269] In another possible implementation, the device is an access network device (e.g., a CU) or is located in the access network device. Specifically, communication unit 1101 is configured to send indication information to the first network device, wherein the indication information is used to determine the first mapping relationship between the first carrier and the second carrier. Communication unit 1101 is further configured to send a first message to the first network device, wherein the first message is a first downlink message sent by the second network device to the first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device.The first carrier is used to transmit the first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between the second terminal device and the first network device. The second terminal device provides a relay service to the first terminal device.

[270] For specific unit execution procedures Petition 870250104104, dated 11 / 13 / 2025, pages 80 / 102 74 / 81 of communication 1101 and processing unit 1102 in this implementation, refer to the descriptions of the steps performed by the second network device in the previous method embodiments and the corresponding descriptions in the summary. Details are not described again in this document. In the communication method implemented by the device, the second network device sends the indication information to the first network device, so that the first network device can determine, based on the indication information, the configuration of the first mapping relationship used to transmit the first message, and the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station.

[271] Figure 12 is a diagram of another communication apparatus according to this application. The communication apparatus is configured to implement the communication methods in the preceding method embodiments. It can be understood that the communication apparatus 1200 includes, for example, a necessary form, such as a module, a unit, an element, a circuit, or an interface, to be appropriately configured together to carry out the method in this application. For example, the communication apparatus 1200 may be a RAN node, a terminal, a core network device, or other network device, or it may be a component (e.g., a chip) in these devices, to implement the methods described in the preceding method embodiments. The communication apparatus 1200 includes one or more processors 1201. The processor 1201 may be a general-purpose processor, a dedicated processor, or the like.For example, the processor can be a baseband processor or a central processing unit. The baseband processor can be configured to process a communication protocol and communication data. The central processing unit can be configured to: control the... Petition 870250104104, dated 11 / 13 / 2025, pages 81 / 102 75 / 81 communication device (e.g., a RAN node, a terminal, or a chip), execute a software program and process data from the software program.

[272] Optionally, processor 1201 may include a program 1202 (which may sometimes also be called code or instructions). Program 1202 may be run on processor 1201, so that communication apparatus 1200 performs the method described in the previous embodiments. In yet another possible design, communication apparatus 1200 includes a circuit (not shown in Figure 12). The circuit is configured to implement a function of the CU or DU in the previous embodiments.

[273] Optionally, the communication apparatus 1200 may include one or more memories 1203, and the memory 1203 stores a program 1204 (which may sometimes also be called code or instructions). The program 1204 may be run on the processor 1201, so that the communication apparatus 1200 performs the method described in the previous method embodiments.

[274] Optionally, processor 1201 and / or memory 1203 may include AI modules 1205 and 1206. The AI ​​module is configured to implement an AI-related function. The AI ​​module may be implemented using software, hardware, or a combination of software and hardware. For example, the AI ​​module may include a RIC module. For example, the AI ​​module may be a near real-time RIC or a non-real-time RIC.

[275] Optionally, the communication apparatus 1200 also includes a transceiver 1207 and an antenna 1208. The transceiver 1207 and the antenna 1208 can implement a transceiver function, for example, communicating with another device by means of a transmission medium, so that the apparatus 1200 can communicate with the other device.

[276] In one possible implementation, the device is a DU or is located in a DU. Specifically, transceiver 1207 and antenna 1208 are configured to receive information from Petition 870250104104, dated 11 / 13 / 2025, pp. 82-102 76 / 81 indication from a second network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier. Transceiver 1207 and antenna 1208 are further configured to receive a first message from the second network device, wherein the first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection. The first connection is a connection between a first terminal device and a second network device, the first carrier is used to transmit a first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between the second terminal device and the first network device.The second terminal device provides a relay service to the first terminal device. Processor 1201 is configured to transmit the first message based on the first mapping relationship.

[277] For a specific execution procedure for the 1200 communication device in this implementation, refer to the descriptions of the steps performed by the first network device in the previous method modes and the corresponding descriptions in the summary. Details are not described again in this document. In the communication method implemented by the device, the DU receives the indication information and determines, based on the indication information, the configuration of the first mapping relationship used to transmit the first message, so that the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station.

[278] In one possible implementation, the device is a CU or is located in a CU. Specifically, the 1207 transceiver Petition 870250104104, dated 11 / 13 / 2025, pp. 83 / 102 Transceiver 77 / 81 and antenna 1208 are configured to send indication information to the first network device, wherein the indication information is used to determine the first mapping relationship between the first carrier and the second carrier. Transceiver 1207 and antenna 1208 are further configured to send a first message to the first network device, wherein the first message is a first downlink message sent by the second network device to the first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device. The first carrier is used to transmit a first message between the first terminal device and the second network device, and the second carrier is used to transmit the first message between the second terminal device and the first network device.The second terminal device provides a relay service to the first terminal device.

[279] For a specific procedure for implementing the 1200 communication device in this implementation, refer to the descriptions of the steps performed by the second network device in the previous method embodiments and the corresponding descriptions in the summary. Details are not described again in this document. In the communication method implemented by the device, the second network device sends the indication information to the first network device, so that the first network device can determine, based on the indication information, the configuration of the first mapping relationship used to transmit the first message, and the first terminal device re-establishes or resumes the first connection through the second terminal device and correctly accesses the base station.

[280] In this application, the processor may be a processor of Petition 870250104104, dated 11 / 13 / 2025, pages 84 / 102 78 / 81 general purpose, a digital signal processor, a specific application integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute methods, steps and logic block diagrams that are disclosed in this application. The general purpose processor may be a microprocessor or any conventional or similar processor. The steps of the methods disclosed with reference to this application may be implemented directly by a hardware processor or may be implemented by a combination of hardware and a software module in a processor.

[281] In this application, memory can be non-volatile memory, for example, a hard disk drive (HDD) or a solid-state drive (SSD), or it can be volatile memory, for example, random-access memory (RAM). Memory is any other medium that can carry or store expected program code in the form of an instruction or data structure and that can be accessed by a computer, but is not limited to that. Memory in this application may alternatively be a circuit or any other device that can implement a storage function and is configured to store program instructions and / or data.

[282] This application provides another communication device. The device includes a processor and an interface. Optionally, a memory is included. The processor is coupled to the memory and configured to read and execute computer instructions stored in the memory, to implement the communication methods in the modes shown in Figures 7 to 10C.

[283] This application provides a communication system. The communication system includes one or more of the devices in the modes shown in Figures 7 to 10C. Petition 870250104104, dated 11 / 13 / 2025, pages 85 / 102 79 / 81

[284] This application provides a computer-readable storage medium. The computer-readable storage medium stores a program or instructions. When the program or instructions are run on a computer, the computer is enabled to perform the communication methods in the modes shown in Figures 7 to 10C.

[285] This application provides a computer program product. The computer program product includes instructions. When the instructions are run on a computer, the computer is enabled to perform the communication methods in the modes shown in Figures 7 to 10C.

[286] This application provides a chip or a chip system. The chip or chip system includes at least one processor and an interface. The interface and the at least one processor are interconnected by a line. The at least one processor is configured to execute a computer program or instructions, to perform the communication methods in the modes shown in Figures 7 to 10C.

[287] The interface on the chip can be an input / output interface, a pin, a circuit, or similar.

[288] The chip system may be a system on a chip (SOC), a baseband chip, or similar. The baseband chip may include a processor, a channel encoder, a digital signal processor, a modem, an interface module, and the like.

[289] In one implementation, the chip or chip system described above in this application further includes at least one memory, and that memory stores instructions. The memory may be a storage unit within the chip, for example, a register or a cache, or it may be a storage unit (for example, a read-only memory or a random-access memory) of the chip.

[290] All or some of the technical solutions provided in this Petition 870250104104, dated 11 / 13 / 2025, pages 86 / 102 Applications 80 / 81 may be implemented using software, hardware, firmware, or any combination thereof. When software is used to implement the applications, all or part of the applications may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the procedure or functions according to this application are wholly or partially generated. The computer may be a general-purpose computer, a dedicated special-purpose computer, a computer network, a network device, a terminal device, or other programmable apparatus. The computer instructions may be stored on a computer-readable storage medium or may be transmitted from one computer-readable storage medium to another computer-readable storage medium.For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired manner (e.g., a coaxial cable, a fiber optic cable, or a digital subscriber line (DSL)) or wirelessly (e.g., infrared, radio, or microwave). Computer-readable storage media can be any usable media accessible by the computer or a data storage device, such as a server or data center, integrating one or more usable media. The usable media can be a magnetic medium (e.g., a floppy disk, a hard disk, or magnetic tape), an optical medium (e.g., a digital video disc (DVD)), a semiconductor medium, or similar.

[291] In this request, based on the principle that there is no logical contradiction, the modalities can be mutually referenced. For example, methods and / or terms can be mutually referenced between modalities of methods. By Petition 870250104104, dated 11 / 13 / 2025, pp. 87 / 102 81 / 81 For example, functions and / or terms can be mutually referenced between apparatus modalities. For example, functions and / or terms can be mutually referenced between an apparatus modality and a method modality.

[292] It is evident that a person skilled in the art may make various modifications and variations to this application without departing from its scope. Thus, this application is intended to encompass such modifications and variations, provided that the modifications and variations fall within the scope of the claims of this application and its equivalent technologies. Petition 870250104104, dated 11 / 13 / 2025, pp. 88 / 102

Claims

1 / 5 CLAIMS 1. A communication method, applied to a first network device or to a chip of the first network device, and characterized in that it comprises: receiving indication information from a second network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier; receiving a first message from the second network device, wherein the first message is a first downlink message sent by the second network device to a first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device;The first carrier is used to transmit the first message between the first terminal device and the second network device; the second carrier is used to transmit the first message between a second terminal device and the first network device; and the second terminal device provides a relay service to the first terminal device; and transmit the first message based on the first mapping relationship.

2. Method according to claim 1, characterized in that receiving the indication information from the second network device comprises: receiving initial indication information from the second network device, wherein the initial indication information indicates a first identifier of the first terminal device, and the first identifier is used by the first network device to associate the first terminal device on an interface between the first network device and the second network device. Petition 870250090366, dated 10 / 03 / 2025, p. 22 / 34 2 / 5 3. A method according to claim 2, characterized in that the indication information is used to determine the first mapping relationship between the first carrier and the second carrier, comprises: obtaining context information from the first terminal device based on the first identifier; and determining the first mapping relationship based on the context information from the first terminal device.

4. Method, according to claim 1 or 2, characterized in that the indication information comprises the first mapping relationship.

5. A method, according to any one of claims 1 to 4, characterized in that the first downlink message is a first reconnection-establishment message, a first reconnection-resume message, or a first connection-release message; and the first carrier is an SRB1 signaling radio carrier message from the first terminal device.

6. A method according to any one of claims 1 to 5, characterized in that the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first terminal device.

7. A communication method, applied to a second network device or to a chip of the second network device, and characterized in that it comprises: sending indication information to a first network device, wherein the indication information is used to determine a first mapping relationship between a first carrier and a second carrier; and sending a first message to the first network device, wherein the first message is a first downlink message sent by the second network device to Petition 870250090366, dated 03 / 10 / 2025, p.23 / 34 3 / 5 a first terminal device in a procedure to re-establish or resume a first connection, and the first connection is a connection between the first terminal device and the second network device; and the first carrier is used to transmit the first message between the first terminal device and the second network device, the second carrier is used to transmit the first message between a second terminal device and the first network device, and the second terminal device provides a relay service to the first terminal device.

8. Method according to claim 7, characterized in that sending the indication information to the first network device comprises: sending initial indication information to the first network device, wherein the initial indication information indicates an initial identifier of the first terminal device, and the initial identifier is used by the first network device to associate the first terminal device on an interface between the first network device and the second network device.

9. A method according to claim 8, characterized in that the first identifier is used by the first network device to obtain context information from the first terminal device, and the context information from the first terminal device comprises the first mapping relationship.

10. Method according to claim 7 or 8, characterized in that the indication information comprises the first mapping relationship.

11. Method, according to any one of claims 7 to 10, characterized in that the first downlink message is a first reconnection message, a first reconnection message, or a first connection release message; and the first carrier is an SRB1 message from the first terminal device.

12. A method according to any one of claims 7 to 10, characterized in that the first downlink message is a first connection rejection message, and the first carrier is an SRB0 message from the first terminal device.

13. Communication apparatus, characterized in that it comprises a processor and a memory, wherein the memory is configured to store instructions and, when the instructions are executed by the processor, the communication apparatus is enabled to perform the method as defined in any one of claims 1 to 6 or 7 to 12.

14. Communication system, characterized in that it comprises one or more of a first network device, a second network device, a first terminal device and a second terminal device, wherein the first network device is configured to perform the method as defined in any one of claims 1 to 6; and the second network device is configured to perform the method as defined in any one of claims 7 to 12.

15. Computer-readable storage medium, characterized in that the computer-readable storage medium stores instructions and, when the instructions are run on a computer, the computer is enabled to perform the method as defined in any one of claims 1 to 6 or 7 to 12.

16. Chip, characterized in that the chip comprises a processor and an interface, and the processor is configured to execute a computer program or instructions, such that the chip implements the method as defined in any one of claims 1 to 6 or 7 to 12.

17. Chip system, characterized in that the chip system comprises a processor and an interface, and the processor is configured to execute a computer program or instructions, such that the chip system implements the method as defined in any one of claims 1 to 6 or 7 to 12.

18. Computer program product, comprising instructions, characterized in that when the instructions are run on a computer, the computer is enabled to perform the method as defined in any one of claims 1 to 6 or 7 to 12. Petition 870250090366, dated 10 / 03 / 2025, pp. 26 / 34

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