Information transmission method, apparatus and device

Abstract

The present application belongs to the technical field of communications. Disclosed are an information transmission method, apparatus and device. The information transmission method in the embodiments of the present application comprises: a source device sending first information to a first candidate device corresponding to a PDCP anchor, wherein the first information comprises at least one of the following: downlink address information of a terminal in a first distributed unit (DU) associated with the PDCP anchor, and related information of a second candidate device associated with the PDCP anchor, the related information comprising at least one of the following: a cell identifier of a candidate cell of the second candidate device, Xn identification information of the second candidate device, identification information of the first DU, and a PLMN of the candidate cell of the second candidate device, the first DU corresponding to the second candidate device, and the second candidate device being different from the first candidate device.

Description

Information transmission methods, devices and equipment

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410950894.4, filed in China on July 16, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of communication technology, specifically relating to an information transmission method, apparatus, and device. Background Technology

[0004] Some communication systems support a Centralized Unit (CU)-Distributed Unit (DU) architecture, meaning a single network-side device includes both a CU and a DU. In some related technologies, the Packet Data Convergence Protocol (PDCP) anchor needs to be changed during certain cell change scenarios, such as cross-CU handover. Since key-related information is provided by the PDCP anchor during cell changes, a key update process is required in cross-CU handover scenarios, leading to higher handover latency. Summary of the Invention

[0005] This application provides an information transmission method, apparatus, and device that can solve the problem of high switching latency.

[0006] Firstly, an information transmission method is provided, including:

[0007] The source device sends first information to the first candidate device corresponding to the PDCP anchor, the first information including at least one of the following:

[0008] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0009] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the Public Land Mobile Network (PLMN) of the candidate cell of the second candidate device.

[0010] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0011] Secondly, an information transmission method is provided, including:

[0012] The first candidate device receives first information sent by the source device. The first candidate device is the device corresponding to the Packet Data Convergence Protocol (PDCP) anchor. The first information includes at least one of the following:

[0013] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0014] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0015] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0016] Thirdly, an information transmission method is provided, including:

[0017] The second candidate device receives the uplink address information of the terminal at the PDCP anchor;

[0018] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0019] Fourthly, an information transmission device is provided, comprising:

[0020] The sending module is configured to send first information to the first candidate device corresponding to the PDCP anchor, wherein the first information includes at least one of the following:

[0021] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0022] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0023] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0024] Fifthly, an information transmission device is provided, comprising:

[0025] The receiving module is used to receive first information sent by the source device, wherein the device corresponding to the device is the device corresponding to the PDCP anchor, and the first information includes at least one of the following:

[0026] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0027] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0028] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0029] Sixthly, an information transmission device is provided, comprising:

[0030] The receiving module is used to receive the uplink address information of the terminal at the PDCP anchor.

[0031] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0032] In a seventh aspect, an information transmission apparatus is provided, the apparatus being configured to perform the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect, or to implement the steps of the method described in the third aspect.

[0033] Eighthly, a network-side device is provided, the terminal including a processor and a memory, the memory storing a program or instructions executable on the processor, wherein the program or instructions, when executed by the processor, implement the steps of the method as described in the first aspect, or the program or instructions, when executed by the processor, implement the steps of the method as described in the second aspect, or the program or instructions, when executed by the processor, implement the steps of the method as described in the third aspect.

[0034] A ninth aspect provides a network-side device, including a processor and a communication interface, wherein the communication interface is used to send first information to a first candidate device corresponding to a PDCP anchor, the first information including at least one of the following: downlink address information of a terminal in a first distribution unit (DU) associated with the PDCP anchor; and relevant information of a second candidate device associated with the PDCP anchor, the relevant information including at least one of the following: cell identifier of a candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; and Public Land Mobile Network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0035] In a tenth aspect, a network-side device is provided, including a processor and a communication interface, wherein the communication interface is used to receive first information sent by a source device, the first candidate device being a device corresponding to a PDCP anchor, the first information including at least one of the following: downlink address information of a terminal in a first distribution unit (DU) associated with the PDCP anchor; and relevant information of a second candidate device associated with the PDCP anchor, the relevant information including at least one of the following: cell identifier of a candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; and Public Land Mobile Network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0036] Eleventhly, a network-side device is provided, including a processor and a communication interface, wherein the communication interface is used to receive uplink address information of a terminal at a PDCP anchor; wherein the second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0037] Eleventhly, a readable storage medium is provided, on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect, or the steps of the method described in the second aspect, or the steps of the method described in the third aspect.

[0038] In a twelfth aspect, a wireless communication system is provided, comprising: a source device, a first candidate device, and a second candidate device, wherein the source device is configured to perform the steps of the method as described in the first aspect, the first candidate device is configured to perform the steps of the method as described in the second aspect, and the second candidate device is configured to perform the steps of the method as described in the third aspect.

[0039] In a thirteenth aspect, a chip is provided, the chip including a processor and a communication interface coupled to the processor, the processor being configured to run programs or instructions to implement the method as described in the first aspect, or the method as described in the second aspect, or the method as described in the third aspect.

[0040] In a fourteenth aspect, a computer program / program product is provided, the computer program / program product being stored in a storage medium, the computer program / program product being executed by at least one processor to implement the steps of the method as described in the first aspect, or the computer program / program product being executed by at least one processor to implement the steps of the method as described in the second aspect, or the computer program / program product being executed by at least one processor to implement the steps of the method as described in the third aspect.

[0041] In this embodiment, the source device sends first information to the first candidate device corresponding to the PDCP anchor. The first information includes at least one of the following: downlink address information of the terminal's first DU associated with the PDCP anchor; and relevant information of the second candidate device associated with the PDCP anchor, including at least one of the following: cell identifier of the candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; and the Public Land Mobile Network (PLMN) of the candidate cell of the second candidate device. The first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device. By sending the downlink address information of the terminal's first DU associated with the PDCP anchor, the PDCP anchor can be associated with the DU of the second candidate device. Sending the relevant information of the second candidate device associated with the PDCP anchor can trigger the PDCP anchor to establish an association with the first DU of the second candidate device, thus achieving the association between the PDCP anchor and the DU of the second candidate device. Therefore, when a cell change occurs between the first and second candidate devices, the changed DU is associated with the aforementioned PDCP anchor, avoiding PDCP anchor changes and eliminating the need for a key update process, thereby reducing handover latency. Attached Figure Description

[0042] Figure 1 is a schematic diagram of a system provided in an embodiment of this application;

[0043] Figure 2 is a schematic diagram of a scenario provided by an embodiment of this application;

[0044] Figure 3 is a flowchart of an information transmission method provided in an embodiment of this application;

[0045] Figure 4 is a schematic diagram of another scenario provided by an embodiment of this application;

[0046] Figure 5 is a flowchart of another information transmission method provided in an embodiment of this application;

[0047] Figure 6 is a flowchart of another information transmission method provided in an embodiment of this application;

[0048] Figure 7 is a schematic diagram of another scenario provided by an embodiment of this application;

[0049] Figure 8 is a schematic diagram of a cell change provided in an embodiment of this application;

[0050] Figure 9 is a schematic diagram of another cell change provided in an embodiment of this application;

[0051] Figure 10 is a structural diagram of an information transmission device provided in an embodiment of this application;

[0052] Figure 11 is a structural diagram of another information transmission device provided in an embodiment of this application;

[0053] Figure 12 is a structural diagram of another information transmission device provided in an embodiment of this application;

[0054] Figure 13 is a structural diagram of a communication device provided in an embodiment of this application;

[0055] Figure 14 is a structural diagram of a network-side device provided in an embodiment of this application. Detailed Implementation

[0056] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0057] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same class, not limited in number; for example, the first object can be one or more. Furthermore, "or" in this application indicates at least one of the connected objects. For example, the scope of protection for "A or B" covers at least three scenarios: Scenario 1: including A but not B; Scenario 2: including B but not A; Scenario 3: including both A and B. In addition, the terms "A and / or B," "at least one of A and B," and "at least one of A or B" also cover at least the above three scenarios. The character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0058] The term "instruction" in this application can be either a direct instruction (or explicit instruction) or an indirect instruction (or implicit instruction). A direct instruction can be understood as one in which the sender explicitly informs the receiver of specific information, the operation to be performed, or the requested result, etc., in the instruction sent. An indirect instruction can be understood as one in which the receiver determines the corresponding information based on the instruction sent by the sender, or makes a judgment and determines the operation to be performed or the requested result, etc., based on the judgment result.

[0059] It is worth noting that the technologies described in this application are not limited to Long Term Evolution (LTE) / LTE-Advanced (LTE-A) systems, but can also be used in other wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency-Division Multiple Access (SC-FDMA), or other systems. The terms "system" and "network" in this application are often used interchangeably, and the described technologies can be used with the systems and radio technologies mentioned above, as well as with other systems and radio technologies. The following description describes New Radio (NR) systems for illustrative purposes, and the term NR is used in most of the following description; however, these technologies can also be applied to systems other than NR systems, such as 6th generation (6G) radio systems. th Generation 6G communication system.

[0060] Figure 1 shows a block diagram of a wireless communication system applicable to an embodiment of this application. The wireless communication system includes a terminal 11 and a network-side device 12. The terminal 11 can be a mobile phone, tablet computer, laptop computer, notebook computer, personal digital assistant (PDA), handheld computer, netbook, ultra-mobile personal computer (UMPC), mobile internet device (MID), augmented reality (AR), virtual reality (VR) device, robot, wearable device, flight vehicle, vehicle user equipment (VUE), shipboard equipment, pedestrian user equipment (PUE), smart home (home devices with wireless communication capabilities, such as refrigerators, televisions, washing machines, or furniture), game console, personal computer (PC), ATM, or self-service machine, etc. Wearable devices include: smartwatches, smart bracelets, smart headphones, smart glasses, smart jewelry (smart bracelets, smart chains, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. Among these, in-vehicle devices can also be referred to as in-vehicle terminals, in-vehicle controllers, in-vehicle modules, in-vehicle components, in-vehicle chips, or in-vehicle units, etc. It should be noted that the specific type of terminal 11 is not limited in this application embodiment. Network-side equipment 12 may include access network equipment or core network equipment, wherein access network equipment may also be referred to as Radio Access Network (RAN) equipment, radio access network function, or radio access network unit. Access network equipment may include base stations, Wireless Local Area Network (WLAN) access points (APs), or Wireless Fidelity (WiFi) nodes, etc.The term "base station" can be referred to as Node B (NB), Evolved Node B (eNB), Next Generation Node B (gNB), New Radio Node B (NR Node B), Access Point, Relay Base Station (RBS), Serving Base Station (SBS), Base Transceiver Station (BTS), Radio Base Station, Radio Transceiver, Basic Service Set (BSS), Extended Service Set (ESS), Home Node B (HNB), Home Evolved Node B, Transmit / Receive Point (TRP), or any other suitable term in the relevant field, as long as the same technical effect is achieved. The term "base station" is not limited to specific technical terms. It should be noted that the embodiments in this application only use base stations in NR systems as examples for description and do not limit the specific type of base station.

[0061] Core network equipment, also known as core network nodes, core network functions, or core network elements, includes, but is not limited to, at least one of the following: Mobility Management Entity (MME), Access and Mobility Management Function (AMF), Session Management Function (SMF), User Plane Function (UPF), Policy Control Function (PCF), Policy and Charging Rules Function (PCRF), Edge Application Server Discovery Function (EASDF), Unified Data Management (UDM), Unified Data Repository (UDR), Home Subscriber Server (HSS), Centralized network configuration (CNC), Network Repository Function (NRF), Network Exposure Function (NEF), Local NEF (or L-NEF), and Binding Support. The core network functions include: BSF (Block Network Function), Application Function (AF), Location Management Function (LMF), Gateway Mobile Location Centre (GMLC), and Network Data Analytics Function (NWDAF). It should be noted that this application embodiment only uses core network equipment in the NR system as an example and does not limit the specific type of core network equipment. If the name of the core network equipment mentioned in this application embodiment changes in subsequent protocol versions (e.g., 6G), it will still be within the scope of protection of this application.

[0062] Optionally, the core network equipment can be implemented by one or more functional modules in a single device, or by multiple devices working together; this application does not specifically limit this. It is understood that the aforementioned functional modules can be network elements in hardware devices, software functional modules running on dedicated hardware, or virtualized functional modules instantiated on a platform (e.g., a cloud platform).

[0063] Taking the 5G New Radio (NR) as an example, the CU-DU architecture is shown in Figure 2. The gNB is split into gNB-CU and gNB-DU, and connected through the F1 interface. A gNB contains only one CU and one or more DUs, and one DU contains one or more cells.

[0064] CU contains protocol stacks at or above PDCP, while DU contains protocol stacks below PDCP, such as Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY).

[0065] In the control plane, the CU includes Radio Resource Control (RRC) and the PDCP of the control plane (PDCP-C).

[0066] On the user plane, the CU includes the Service Data Adaptation Protocol (SDAP) and the user plane PDCP (PDCP-U).

[0067] It should be noted that Figure 2 is only an example of a 5G system, and the embodiments of this application can be applied to 5G, 6G or 7th generation (7G). th Communication systems such as Generation 7G (7G) and others.

[0068] The following description, in conjunction with the accompanying drawings, details an information transmission method, apparatus, and device provided in this application through some embodiments and application scenarios.

[0069] Please refer to Figure 3, which is a flowchart of an information transmission method provided in an embodiment of this application. As shown in Figure 3, it includes the following steps:

[0070] Step 301: The source device sends first information to the first candidate device corresponding to the PDCP anchor, the first information including at least one of the following:

[0071] The terminal's downlink address information for the first DU associated with the PDCP anchor;

[0072] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0073] The aforementioned source device can be an access network device, such as a radio access network device that decides to perform a cell change; or a radio access network device that initiates a cell change preparation process to support continuous cell changes.

[0074] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0075] In this embodiment, a PDCP anchor can be understood as a node or device that can provide key-related information during cell change processes, such as a node or device that can provide key-related information during continuous serving cell changes. In this embodiment, the name of the PDCP anchor is not limited; it can be replaced with key-providing node, key-providing device, key-associating device, key node, or key device, etc.

[0076] The first candidate device corresponding to the above PDCP anchor can be understood as the first candidate device including the PDCP anchor, such as the user plane (UP) of the CU of the first candidate device being the PDCP anchor, or the UP of the first candidate device being the PDCP anchor.

[0077] The correspondence between the first DU and the second candidate device can be understood as the first DU being one or more DUs of the second candidate device, that is, the CU of the second candidate device can directly control the first DU, and the two are in the same wireless access network device.

[0078] The first DU mentioned above can also be called a candidate DU.

[0079] The first and second candidate devices mentioned above can be two different candidate access network devices, such as candidate gNB.

[0080] The downlink address information of the terminal in the first DU associated with the PDCP anchor can be the downlink address information of the terminal in the user plane (F1-U) of the F1 interface of the first DU, such as the F1-U downlink tunnel endpoint identifier (TEID).

[0081] It should be noted that, in cases where the aforementioned first information does not include the aforementioned related information, since the PDCP directly corresponding to the first DU is the PDCP of the second candidate device, not the PDCP of the first candidate device, the first DU and the PDCP anchor are not associated. Sending the downlink address information of the first DU associated with the PDCP anchor to the first candidate device corresponding to the PDCP anchor enables the PDCP anchor to be associated with the first DU. Thus, when cell changes occur between the first and second candidate devices, since both the DU before and after the change are associated with the aforementioned PDCP anchor, PDCP anchor changes are avoided, and therefore, a key update process is unnecessary. This avoids key updates when the terminal moves between candidate cells corresponding to the same PDCP anchor, thereby reducing handover latency, i.e., reducing cell change latency.

[0082] In addition, by sending the downlink address information of the first terminal in the first DU, the PDCP anchor can establish a user plane channel with the first DU based on the downlink address information. In this way, data transmission can be carried out directly between the first DU and the PDCP anchor without going through the forwarding of the CU corresponding to the first DU, thereby reducing data transmission latency.

[0083] The aforementioned first information, including the relevant information of the second candidate device associated with the PDCP anchor, can be understood as the PDCP anchor being associated with the second candidate device, and the first DU corresponding to the second candidate device, thereby realizing the association between the PDCP anchor and the first DU.

[0084] It should be noted that, in the absence of the downlink address information mentioned above in the first information, the relevant information of the second candidate device associated with the PDCP anchor can enable the first candidate device associated with the PDCP anchor to actively establish an association with the first DU by going to the second candidate device. Since the first DU corresponds to the second candidate device, the PDCP anchor can be associated with the first DU. Thus, when cell change is performed between the first candidate device and the second candidate device, since the DU before and after the change is associated with the PDCP anchor, the PDCP anchor change is avoided, and therefore the key update process is not required. This avoids the key update when the terminal moves between candidate cells corresponding to the same PDCP anchor, thereby reducing handover latency, i.e., reducing cell change latency.

[0085] The aforementioned information includes the cell identifier of the candidate cell of the second candidate device. The PDCP anchor can send this information to the second candidate device, so that the second candidate device can index its associated DU, i.e., the first DU, based on the identifier of the candidate cell, thereby helping to establish the association between the PDCP anchor and the first DU, which is beneficial to reducing handover latency.

[0086] The aforementioned relevant information includes the Xn identifier information of the second candidate device. Based on this Xn identifier information, the PDCP anchor can identify the second device and send the interface-related information for establishing an association between the PDCP anchor and the first DU to the second device. The second device can then forward the response message from the first DU to the PDCP anchor, thereby helping to establish the association between the PDCP anchor and the first DU and reducing handover latency.

[0087] The aforementioned information includes the identification information of the first DU. This allows the PDCP anchor to determine the information of the first DU that needs to be associated and send this information to the second device. The second device then helps establish the association between the PDCP anchor and the first DU, which helps reduce handover latency.

[0088] The aforementioned information includes the PLMN of the candidate cell of the second candidate device. The PDCP anchor can send this information to the second candidate device, so that the second candidate device can index its associated DU, i.e., the first DU, based on the PLMN of the candidate cell. This helps to establish the association between the PDCP anchor and the first DU, which is beneficial to reducing handover latency.

[0089] In some implementations, the PDCP anchor can obtain the downlink address information of the terminal in the first DU based on the aforementioned relevant information. For example, the first candidate device requests the downlink address information from the second candidate device. This enables the PDCP anchor to establish a user plane channel with the first DU based on the downlink address information. In this way, data transmission can be directly transmitted between the first DU and the PDCP anchor without going through the forwarding of the CU corresponding to the first DU, thereby reducing data transmission latency.

[0090] In some implementations, the first information may be obtained from the second candidate device, or it may be pre-configured by the source device, or it may be obtained from the core network. In this application embodiment, the method of obtaining the first information is not limited.

[0091] In this embodiment of the application, the DU of the second candidate device can be associated with the PDCP anchor through the above steps. In this way, when cell change is performed between the first candidate device and the second candidate device, the changed DU is associated with the above PDCP anchor, thereby avoiding PDCP anchor change and eliminating the need for key update process, reducing handover latency, i.e. reducing cell change latency.

[0092] For example, as shown in Figure 4, assuming the first candidate device is gNB#0, and gNB#0's CU UP0 is the PDCP anchor, the second candidate device is gNB#1, gNB#0's second DU (i.e., DU0) is in cell#0, and gNB#1's first DU (i.e., DU1) is in cell#1. Through the above steps, the PDCP anchor is associated with gNB#1's first DU (i.e., DU1), thus making gNB#0's CU UP0 the PDCP anchor for both gNB#0's second DU (i.e., DU0) and gNB#1's first DU (i.e., DU1). This way, the terminal does not need to perform a key update when the UE moves from Cell#0 to Cell#1, or from Cell#1 to Cell#0.

[0093] As an optional implementation, the method further includes:

[0094] The source device sends second information to the second candidate device, the second information including:

[0095] The terminal's uplink address information on the PDCP anchor.

[0096] The aforementioned uplink address information can be the F1-U uplink address information.

[0097] In this embodiment, by sending the second information to the second candidate device, a user plane channel can be established between the first DU of the second candidate device and the PDCP anchor. In this way, data transmission can be directly transmitted between the first DU and the PDCP anchor without going through the forwarding of the CU corresponding to the first DU, thereby reducing data transmission latency.

[0098] It should be noted that the embodiments of this application do not limit the above-mentioned uplink address information to be sent from the source device to the second candidate device. For example, in some embodiments, the above-mentioned uplink address information may also be sent from the first candidate device to the second candidate device.

[0099] In some implementations, the second information may be obtained from the first candidate device, pre-configured by the source device, or obtained from the core network. In this application embodiment, the method of obtaining the second information is not limited.

[0100] In some implementations, the uplink address information of the PDCP anchor can be requested by the source device from the first candidate device. For example, the source device requests F1-U uplink address information from the PDCP anchor and sends the uplink address information of the PDCP anchor to its associated second candidate device; the source device requests F1-U downlink address information from the first DU associated with the second candidate device and sends the downlink address information of the second candidate device to the first candidate device corresponding to its associated PDCP anchor.

[0101] In some implementations, the uplink address information of the terminal at the PDCP anchor may also be actively sent by the first candidate device to the source device.

[0102] As an optional implementation, the method further includes:

[0103] The source device sends a first request to the first candidate device, the first request including at least one of the following:

[0104] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for the inter-CU serving cell change, wherein the inter-CU serving cell change supports not updating the key, or the inter-CU serving cell change supports not involving PDCP anchor change.

[0105] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0106] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0107] Protocol Data Unit (PDU) session information;

[0108] Data Radio Bearer (DRB) information;

[0109] Signaling Radio Bearer (SRB) information.

[0110] The first request mentioned above can be a HANDOVER REQUEST or an S-NODE Addition REQUEST.

[0111] The aforementioned serving cell change can be a Layer 1 / Layer 2-triggered mobility (LTM) or other serving cell changes, and there are no restrictions on this.

[0112] The aforementioned inter-CU serving cell change refers to cross-CU cell change.

[0113] The above-mentioned support for inter-CU serving cell changes without updating the key can be understood as the support for inter-CU serving cell changes without updating the key. The above-mentioned support for inter-CU serving cell changes without involving PDCP anchor changes can be understood as the support for inter-CU serving cell changes without involving PDCP anchor changes, that is, the PDCP anchor of the source cell is still maintained after the inter-CU cell change is performed.

[0114] The first instruction information enables the first candidate device to execute the corresponding process for changing the serving cell between CUs, thereby achieving a serving cell change without key change and reducing cell change latency.

[0115] In some implementations, cell changes can be performed by default without changing the key or the PDCP anchor, meaning that the first request may not carry the first instruction information.

[0116] The aforementioned second indication information indicates that the first candidate device, as the device corresponding to the PDCP anchor, can enable the PDCP anchor to be specified by the source device, which can improve the flexibility of cell changes.

[0117] In some implementations, the device corresponding to the PDCP anchor can also be pre-designated, such as pre-designating the first candidate device as the device corresponding to the PDCP anchor. That is, the first request may not include the second indication information.

[0118] The above association information can be used to notify the candidate device PDCP anchor of its association with the corresponding second candidate device, DU, or CU. In this case, the association between the PDCP anchor and the second candidate device or CU also realizes the association between the PDCP anchor and the corresponding first DU, because the second candidate device, CU, and DU are inherently associated.

[0119] By sending the aforementioned association information, the PDCP anchor can be assisted in establishing an association with the corresponding second candidate device, DU, or CU. This eliminates the need to change the PDCP anchor during cell changes, thus saving cell change latency.

[0120] It should be noted that in some implementations, the aforementioned association information may be pre-configured to the first candidate device, meaning that the first request may not carry the aforementioned association information.

[0121] The PDU session information mentioned above can be a list of PDU session resources to be set up.

[0122] The PDU session information mentioned above can assist or suggest that the PDCP anchor establish a PDU session in order to improve session performance.

[0123] In some implementations, the aforementioned PDU session information may not be carried.

[0124] The aforementioned DRB information can be suggested DRB information, that is, DRB information suggested by the source device to be established by the PDCP anchor node, such as suggested DRB identifier, suggested Quality of Service (QoS) flow and DRB mapping relationship, etc.

[0125] The aforementioned DRB information can assist PDCP anchor nodes in establishing DRBs, thereby improving data transmission performance.

[0126] In some implementations, the aforementioned DRB information may not be carried.

[0127] The aforementioned SRB information can be suggested SRB information, that is, SRB information suggested by the source device for the PDCP anchor node to establish, such as suggested SRB identifiers and other information.

[0128] The aforementioned SRB information can assist PDCP anchor nodes in establishing SRBs, thereby improving signaling transmission performance.

[0129] In some implementations, the aforementioned SRB information may not be carried.

[0130] Optionally, the method further includes:

[0131] The source device receives a first response sent by the first candidate device, the first response including at least one of the following:

[0132] Established DRB information;

[0133] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0134] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0135] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0136] The DRB information of the second DU corresponding to the PDCP anchor.

[0137] The first response mentioned above can be a HANDOVER REQUEST ACKNOWLEDGE message or an S-NODE ADDITION REQUEST ACKNOWLEDGE message.

[0138] The DRB information established above refers to the DRB information established by the PDCP anchor or the first candidate device.

[0139] The CU corresponding to the aforementioned PDCP anchor can be understood as the CU in the first candidate device mentioned above.

[0140] The second DU corresponding to the aforementioned PDCP anchor can be understood as one or more DUs of the aforementioned first candidate device.

[0141] The DRB information established above may involve multiple DRBs, each DRB corresponding to an uplink address information (UL TNL Information), or the DRB information may include the uplink address information of the terminal on the PDCP anchor. The DRB information may indicate the number of user plane transmission address information corresponding to the PDCP anchor, that is, the DRB information may contain one or more DRB identifiers and the uplink address information of the associated PDCP anchor.

[0142] It should be noted that the embodiments of this application do not limit the way in which the source device obtains the uplink address information of the terminal at the PDCP anchor. For example, it may obtain the uplink address information of the terminal at the PDCP anchor through the first response mentioned above, or the source device may receive the uplink address information of the terminal at the PDCP anchor actively sent by the first candidate device.

[0143] The DRB information established above can be one or more copies. When it is one copy, all DUs that share a PDCP anchor correspond to this information. When it is multiple copies, each DU / candidate cell corresponds to one copy of the information, and each copy of the information contains its corresponding DU identifier / cell identifier.

[0144] In some implementations, the RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information.

[0145] The above RRC configuration information can be one or more copies. When it is one copy, all DUs associated with the same PDCP anchor correspond to this information. When it is multiple copies, each DU / candidate cell corresponds to one copy of the information, and each copy of the information contains its corresponding DU identifier / cell identifier.

[0146] In some implementations, the RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information, which may include RLC configuration information.

[0147] In some implementations, the RRC configuration information generated by the second DU is generated based on the established DRB information, which makes the RRC configuration information match the established DRB information, thereby improving the transmission performance of the terminal.

[0148] The aforementioned F1 interface identifier can be an F1AP ID, such as gNB-CU UE F1AP ID.

[0149] The DRB information of the second DU can be a DRB ID, and the DRB information can correspond one-to-one with the downlink address information, which is used to indicate the user plane transmission address information corresponding to the second DU.

[0150] The DRB information of the second DU can be generated based on the established DRB information, which makes the DRB of the second DU more reliable.

[0151] In the above embodiments, since the DRB information, RRC configuration information or F1 interface identifier are received through the first response, the corresponding configuration or information of the target cell can be applied in the subsequent cell change process to improve the terminal's working performance.

[0152] As an optional implementation, the method further includes:

[0153] The source device sends a second request to the second candidate device, the second request including at least one of the following:

[0154] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0155] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the PLMN identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0156] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0157] DRB information;

[0158] SRB information.

[0159] The second request mentioned above can be a HANDOVER REQUEST or an S-NODE Addition REQUEST.

[0160] The aforementioned first instruction information, associated information, DRB information, and SRB information are described in the corresponding description of the implementation method of the first request, and will not be repeated here, and can achieve the same beneficial effects.

[0161] The PDCP anchor information mentioned above enables the first DU in the second candidate device to be associated with the PDCP anchor, so as to establish a user plane channel with the PDCP anchor and save data transmission latency.

[0162] In some implementations, the PDCP anchor information can also be sent from the first candidate device to the second candidate device.

[0163] Optionally, the method further includes:

[0164] The source device receives a second response sent by the second candidate device, the second response including at least one of the following:

[0165] The RRC configuration information generated by the first DU;

[0166] The terminal is identified by the F1 interface of the first DU;

[0167] The DRB information of the first DU.

[0168] The second response mentioned above can be a HANDOVER REQUEST ACKNOWLEDGE message or an S-NODE ADDITION REQUEST ACKNOWLEDGE message.

[0169] The aforementioned RRC configuration information may include cell group configuration information, which in turn includes RLC configuration information.

[0170] In some implementations, the RRC configuration information generated by the first DU is generated based on at least one of the DRB information and SRB information included in the second request. This makes the RRC configuration information generated based on the source device's suggestion, thereby making the RRC configuration information more reliable.

[0171] The DRB information of the first DU can be a DRB ID, or the DRB information can include the downlink address information of the terminal in the first DU, or it can be understood that the DRB information and the downlink address information can be in one-to-one correspondence, used to indicate the user plane transmission address information corresponding to the first DU, that is, the DRB information can include one or more DRB identifiers and the downlink address information of the first DU.

[0172] It should be noted that, in the embodiments of this application, the method by which the source device obtains the downlink address information of the terminal in the first DU is not limited. For example, it can be obtained through the second response mentioned above, or it can be obtained by receiving the downlink address information of the terminal in the first DU sent by the second candidate device through other messages, such as the downlink address information of the terminal in the first DU actively sent by the second candidate device.

[0173] In some implementations, the DRB information of the first DU is generated based on at least one of the DRB information and SRB information included in the second request, so that the DRB of the first DU is generated based on the source device suggestion, thereby improving the transmission performance of the DRB of the first DU.

[0174] The aforementioned F1 interface identifier can be an F1AP ID, such as gNB-DU UE F1AP ID.

[0175] Since the DRB information, RRC configuration information, or F1 interface identifier are received through the second response, the corresponding configuration or information of the target cell can be applied during subsequent cell changes to improve terminal performance.

[0176] As an optional implementation, the method includes:

[0177] The source device sends a configuration update request to the second candidate device, the configuration update request including at least one of the following:

[0178] The second information;

[0179] Established DRB information;

[0180] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0181] The identification information of the first DU;

[0182] Identification information of candidate communities.

[0183] The aforementioned configuration update request is used to request the second candidate device to update the corresponding configuration.

[0184] The above method includes the step of sending second information from the source device to the second candidate device, which includes: the source device sending a configuration update request to the second candidate device, wherein the configuration update request includes the second information.

[0185] Since the configuration update request includes the second information mentioned above, this avoids introducing other message transmissions, thus saving transmission overhead.

[0186] The method described above, including the steps described above, may further include: the source device sending a configuration update request to the second candidate device, wherein the configuration update request does not include the second information described above. For example, in some embodiments, the second information may be sent by other messages besides the configuration update request, such as through additional notification messages.

[0187] The DRB information established above can be the DRB information established in the first response mentioned above.

[0188] The DRB information established above can be used to update the DRB, thereby improving data transmission performance.

[0189] The third instruction information mentioned above informs the second candidate device to perform a cell change process without key update.

[0190] In some implementations, it can also be assumed that the configuration update between CUs is keyless, that is, the second configuration update request mentioned above does not include the third indication information mentioned above.

[0191] The identification information of the first DU and the candidate cell can be used to indicate the DU and candidate cell participating in the cell change, so that the second candidate device can perform the corresponding operation.

[0192] Optionally, the method further includes:

[0193] The source device receives a configuration update request response from the second candidate device, the configuration update request response including at least one of the following:

[0194] The DRB information updated by the first DU;

[0195] The first DU updates the RRC configuration information.

[0196] The updated DRB information described above enables DRB updates, thereby improving data transmission performance.

[0197] The updated RRC configuration information described above can be used to update the RRC configuration and improve terminal performance.

[0198] As an optional implementation, the source device sending first information to the first candidate device corresponding to the PDCP anchor includes:

[0199] The source device sends a first notification message to the first candidate device corresponding to the PDCP anchor. The first notification message includes the first information and also includes at least one of the following:

[0200] The terminal is identified by the F1 interface of the first DU;

[0201] The DRB information of the first DU.

[0202] In this embodiment, the aforementioned first information can be sent via a first notification message.

[0203] In some implementations, the first information can also be sent via other messages, and the timing of sending the first information is not limited.

[0204] The DRB information of the first DU mentioned above can be obtained through the second response or configuration update request response or other means.

[0205] In this embodiment, sending the F1 interface identifier to the first candidate device enables the first candidate device to communicate directly with the first DU based on the F1 interface identifier, thereby providing services to the terminal and improving terminal performance.

[0206] In this embodiment, sending the DRB information of the first DU to the first candidate device enables the first candidate device to directly provide services to the terminal based on the DRB information, thereby improving the terminal performance.

[0207] As an optional implementation, the source device sends second information to the second candidate device, including:

[0208] The source device sends a second notification message to the second candidate device, the second notification message including the second information, and also including at least one of the following:

[0209] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0210] The DRB information of the PDCP anchor;

[0211] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0212] The DRB information of the aforementioned PDCP anchor may include the established DRB information.

[0213] In this embodiment, the second information can be sent via the second notification message, and at least one of the above-mentioned features can also be included, which can save transmission overhead and eliminate the need to send the second information via an additional message.

[0214] Since the second notification message includes the F1 interface identifier of the CU corresponding to the PDCP anchor for the terminal, the second candidate device can communicate with the PDCP anchor based on the interface identifier to provide services to the terminal and improve terminal performance.

[0215] Since the second notification message includes the DRB information of the PDCP anchor, the second candidate device can provide services to the terminal based on the DRB information, thereby improving the terminal performance.

[0216] The aforementioned fourth instruction information can be used to instruct keyless CUs to change the serving cell, thereby enabling the second candidate device to execute the corresponding procedure. In some implementations, the keyless CU-to-serving cell change can be performed by default, i.e., the aforementioned fourth instruction information is not sent.

[0217] The fourth indication information is used to indicate that the first candidate device can be directly transmitted to the first DU. Based on the above content, the first DU will directly send the message to the first DU without adding or modifying any information, so as to improve terminal performance.

[0218] As an optional implementation, the source device sends first information to the first candidate device corresponding to the PDCP anchor, including:

[0219] The source device sends a first message to the first candidate device corresponding to the PDCP anchor. The first message includes relevant information about the second candidate device, and also includes at least one of the following:

[0220] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0221] PDU session information;

[0222] DRB information;

[0223] SRB information.

[0224] The PDU session information, DRB information and SRB information mentioned above refer to the corresponding content of the first request in the above embodiments, and will not be repeated here, and can achieve the same beneficial effect.

[0225] In this embodiment, the first candidate device is indicated by the fifth indication information as the device corresponding to the PDCP anchor. Thus, the first candidate device can obtain the terminal's address information in the second candidate device based on the relevant information of the second candidate device, such as obtaining the terminal's downlink address information in the first DU, so as to establish a user transmission channel with the second candidate device or the first DU. This ensures that the PDCP anchor does not need to be changed during the cell change process, thereby reducing cell change latency.

[0226] It should be noted that the embodiments of this application are not limited to sending the relevant information of the second candidate device through the first message described above. For example, the content of the first message may carry at least one of the above-mentioned items, while the relevant information of the second candidate device may be sent through other messages.

[0227] As an optional implementation, the method further includes:

[0228] The source device receives a second message sent by the first candidate device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0229] Configuration information related to the CU of the first candidate device;

[0230] Configuration information related to the DU of the second candidate device.

[0231] The aforementioned service cell change candidate configuration information can be LTM candidate configuration information.

[0232] In this embodiment, at least one of the above configuration information can be obtained, so that the source device can send this configuration information to the terminal, thereby enabling the terminal to perform cell change based on this configuration information.

[0233] Optionally, the method further includes:

[0234] The source device sends a serving cell change preparation request or a serving cell change preparation modification request to the first candidate device.

[0235] Among them, the aforementioned serving cell change preparation request can be an LTM preparation request, and the aforementioned serving cell change preparation modification request can be an LTM preparation modification request.

[0236] In this implementation, the aforementioned serving cell change candidate configuration information can be obtained through a serving cell change preparation request or a serving cell change preparation modification request, so as to enable the serving cell change candidate configuration information to be sent on demand, thereby saving transmission overhead.

[0237] In some implementations, the aforementioned serving cell change candidate configuration information may also be actively sent from the first candidate device to the source device.

[0238] Optionally, before the source device sends a serving cell change preparation request or a serving cell change preparation modification request to the first candidate device, the method further includes:

[0239] The source device receives indication information sent by the first candidate device, the indication information being used to indicate at least one of the following:

[0240] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0241] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0242] In this implementation, when the CU corresponding to the PDCP anchor has obtained the information of the first DU or the CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU, the aforementioned serving cell change preparation request or serving cell change preparation modification request can be sent in a timely manner to obtain the complete candidate cell configuration information of the terminal, so as to further reduce the cell change latency overhead.

[0243] As an optional implementation, the method further includes:

[0244] The source device acquires capability information of at least one of the first candidate device and the second candidate device, wherein the capability information represents at least one of the following:

[0245] Supports keyless update for serving cell changes between CUs;

[0246] It supports one DU connecting to multiple CUs.

[0247] Supporting one DU to connect to multiple CUs can be understood as supporting serving cell changes between CUs without key updates.

[0248] The aforementioned capability information can determine that at least one of the first and second candidate devices supports serving cell changes between CUs without key updates, thereby avoiding sending relevant information to devices that do not support this function and saving signaling overhead on the source device.

[0249] In some implementations, the source device may also default to the first and second candidate devices supporting the above capabilities, thereby saving transmission overhead.

[0250] In this embodiment, the source device sends first information to the first candidate device corresponding to the PDCP anchor. The first information includes at least one of the following: downlink address information of the terminal's first DU associated with the PDCP anchor; and relevant information of the second candidate device associated with the PDCP anchor, including at least one of the following: cell identifier of the candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; and the Public Land Mobile Network (PLMN) of the candidate cell of the second candidate device. The first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device. By sending the downlink address information of the terminal's first DU associated with the PDCP anchor, the PDCP anchor can be associated with the DU of the second candidate device. Sending the relevant information of the second candidate device associated with the PDCP anchor can trigger the PDCP anchor to establish an association with the first DU of the second candidate device, thus achieving the association between the PDCP anchor and the DU of the second candidate device. Therefore, when a cell change occurs between the first and second candidate devices, the changed DU is associated with the aforementioned PDCP anchor, avoiding PDCP anchor changes and eliminating the need for a key update process, thereby reducing handover latency.

[0251] Please refer to Figure 5, which is a flowchart of another information transmission method provided in an embodiment of this application. As shown in Figure 5, it includes the following steps:

[0252] Step 501: The first candidate device receives first information sent by the source device. The first candidate device is the device corresponding to the Packet Data Convergence Protocol anchor (PDCP). The first information includes at least one of the following:

[0253] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0254] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0255] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0256] Optionally, the method further includes:

[0257] The first candidate device receives a first request sent by the source device, the first request including at least one of the following:

[0258] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0259] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0260] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0261] Protocol Data Unit (PDU) session information;

[0262] Data wirelessly carries DRB information;

[0263] Signaling radio bearer SRB information.

[0264] Optionally, the method further includes:

[0265] The first candidate device sends a first response to the source device, the first response including at least one of the following:

[0266] Established DRB information;

[0267] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0268] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0269] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0270] The DRB information of the second DU corresponding to the PDCP anchor.

[0271] Optionally, the content of the first response satisfies at least one of the following:

[0272] The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information;

[0273] The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information;

[0274] The DRB information of the second DU is generated based on the established DRB information;

[0275] The RRC configuration information generated by the second DU is generated based on the established DRB information.

[0276] Optionally, the first candidate device receiving the first information sent by the source device includes:

[0277] The first candidate device receives a first notification message sent by the source device, the first notification message including the first information, and further including at least one of the following:

[0278] The terminal is identified by the F1 interface of the first DU;

[0279] The DRB information of the first DU.

[0280] Optionally, the first candidate device receives first information sent by the source device, including:

[0281] The first candidate device receives a first message sent by the source device, the first message including the identification information of the second candidate device, and also including at least one of the following:

[0282] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0283] PDU session information;

[0284] DRB information;

[0285] SRB information.

[0286] Optionally, the method further includes:

[0287] The first candidate device sends a third message to the second candidate device, the third message being used to request the establishment of a user plane data transmission channel with the first DU.

[0288] In this embodiment, the third message mentioned above can be used to establish a user plane data transmission channel with the first DU, thereby reducing data transmission latency.

[0289] Optionally, the third message includes at least one of the following:

[0290] The terminal is identified by the Xn interface of the first candidate device;

[0291] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0292] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0293] Established DRB information;

[0294] The terminal's uplink address information at the PDCP anchor;

[0295] The identification information of the first DU;

[0296] The identification information of the candidate cell associated with the PDCP anchor.

[0297] The content of the third message mentioned above can be found in the corresponding description of the embodiment shown in Figure 3, and will not be repeated here.

[0298] The content included in the third message above makes it easier to establish a user plane data transmission channel between the first candidate device and the first DU.

[0299] In some implementations, the uplink address information of the aforementioned terminal at the PDCP anchor may also be sent to the second candidate device via a message other than the aforementioned third message.

[0300] Optionally, the method further includes:

[0301] The first candidate device receives a fourth message sent by the second candidate device, the fourth message including at least one of the following:

[0302] The terminal is identified by the Xn interface of the second candidate device;

[0303] The terminal is identified by the F1 interface of the first DU;

[0304] DRB information of the first DU;

[0305] The terminal's downlink address information in the first DU;

[0306] The RRC configuration information of the first DU.

[0307] The content of the fourth message mentioned above can be found in the corresponding description of the embodiment shown in Figure 3, and will not be repeated here.

[0308] The content included in the fourth message above makes it easier to establish a user plane data transmission channel between the first candidate device and the first DU.

[0309] Optionally, the method further includes:

[0310] The first candidate device sends a second message to the source device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0311] Configuration information related to the CU of the first candidate device;

[0312] Configuration information related to the DU of the second candidate device.

[0313] Optionally, the method further includes:

[0314] The first candidate device receives a serving cell change preparation request or a serving cell change preparation modification request sent by the source device.

[0315] Optionally, before the first candidate device receives the serving cell change preparation request or serving cell change preparation modification request sent by the source device, the method further includes:

[0316] The first candidate device sends indication information to the source device, the indication information indicating at least one of the following:

[0317] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0318] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0319] Optionally, the method further includes:

[0320] The first candidate device sends capability information to the source device, the capability information representing at least one of the following:

[0321] Supports keyless update for serving cell changes between CUs;

[0322] It supports one DU connecting to multiple CUs.

[0323] It should be noted that this embodiment is an implementation of the first candidate device corresponding to the embodiment shown in FIG3. For the specific implementation, please refer to the relevant description of the embodiment shown in FIG3. In order to avoid repeated description, this embodiment will not be repeated.

[0324] Please refer to Figure 6, which is a flowchart of another information transmission method provided in an embodiment of this application. As shown in Figure 6, it includes the following steps:

[0325] Step 601: The second candidate device receives the uplink address information of the PDCP anchor;

[0326] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0327] Optionally, the second candidate device receives the uplink address information of the terminal at the PDCP anchor, including:

[0328] The second candidate device receives second information sent by the source device, the second information including:

[0329] The terminal's uplink address information on the PDCP anchor.

[0330] Optionally, the method further includes:

[0331] The second candidate device receives a second request sent by the source device, the second request including at least one of the following:

[0332] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0333] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the Public Land Mobile Network (PLMN) identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0334] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0335] DRB information;

[0336] SRB information.

[0337] Optionally, the method further includes:

[0338] The second candidate device sends a second response to the source device, the second response including at least one of the following:

[0339] The RRC configuration information generated by the first DU;

[0340] The terminal is identified by the F1 interface of the first DU;

[0341] The DRB information of the first DU.

[0342] Optionally, the method includes:

[0343] The second candidate device receives a configuration update request sent by the source device, the configuration update request including at least one of the following:

[0344] The second information;

[0345] Established DRB information;

[0346] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0347] The identification information of the first DU;

[0348] Identification information of candidate communities.

[0349] Optionally, the method further includes:

[0350] The second candidate device receives a configuration update request sent by the source device, the configuration update request including at least one of the following:

[0351] Established DRB information;

[0352] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0353] The identification information of the first DU;

[0354] Identification information of candidate communities.

[0355] Optionally, the second candidate device receives the uplink address information of the terminal at the PDCP anchor, including:

[0356] The second candidate device receives a second notification message sent by the source device. The second notification message includes the uplink address information of the terminal at the PDCP anchor, and also includes at least one of the following:

[0357] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0358] The DRB information of the PDCP anchor;

[0359] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0360] Optionally, the second candidate device receives the uplink address information of the terminal at the PDCP anchor, including:

[0361] The second candidate device receives a third message sent by the first candidate device. The third message is used to request the establishment of a user plane data transmission channel with the first DU, and the third message includes the uplink address information of the terminal at the PDCP anchor.

[0362] Optionally, the third message further includes at least one of the following:

[0363] The terminal is identified by the Xn interface of the first candidate device;

[0364] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0365] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0366] Established DRB information;

[0367] The identification information of the first DU;

[0368] The identification information of the candidate cell associated with the PDCP anchor.

[0369] Optionally, the method further includes:

[0370] The second candidate device sends a fourth message to the first candidate device, the fourth message including at least one of the following:

[0371] The terminal is identified by the Xn interface of the second candidate device;

[0372] The terminal is identified by the F1 interface of the first DU;

[0373] DRB information of the first DU;

[0374] The terminal's downlink address information in the first DU;

[0375] The RRC configuration information of the first DU.

[0376] Optionally, the method further includes:

[0377] The second candidate device sends capability information to the source device, the capability information representing at least one of the following:

[0378] Supports keyless update for serving cell changes between CUs;

[0379] It supports one DU connecting to multiple CUs.

[0380] It should be noted that this embodiment is an implementation of the second candidate device corresponding to the embodiments shown in Figures 3 and 5. For the specific implementation, please refer to the relevant descriptions of the embodiments shown in Figures 3 and 5. In order to avoid repeated descriptions, this embodiment will not be repeated.

[0381] The following example illustrates the method provided in this application: The source device and candidate device are both gNBs, and the serving cell is changed to LTM.

[0382] Embodiment 1 of the present invention:

[0383] The source gNB requests address information for all candidate gNBs, specifically:

[0384] The source gNB requests uplink address information (F1-U UL address information) from the PDCP anchor and sends the uplink address information of the PDCP anchor to its associated candidate gNB-DU;

[0385] The source gNB requests F1-UDL address information from the DU associated with the candidate gNB (i.e., the second candidate device mentioned above) that is not a PDCP anchor, and sends the DL address information of the candidate gNB to the gNB corresponding to its associated PDCP anchor (i.e., the first candidate device mentioned above).

[0386] As shown in Figure 7, assuming the UE is in gNB#0, gNB#0 performs the LTM preparation procedure to configure LTM candidate cells for the UE. gNB#0 selects cell#0 / #1 / #2 / #3 as candidate cells and determines that CU UP0 of gNB#0 is the PDCP anchor of DU0 of gNB#0 and DU1 of gNB#1; and determines that CU UP2 of gNB#2 is the PDCP anchor of DU2 of gNB#2 and DU3 of gNB#3.

[0387] Therefore, when the UE moves from Cell#0 to Cell#1, or from Cell#1 to Cell#0, or from Cell#2 to Cell#3, or from Cell#3 to Cell#2, no key update is required.

[0388] The specific process is shown in Figure 8, including the following steps:

[0389] Step 0.0. The UE is in connected state.

[0390] Step 1. The UE performs measurement reporting.

[0391] Step 2. The source gNB decides to perform LTM preparation. The source gNB decides to perform inter-CU LTM without key updates or to not change the PDCP node during inter-CU LTM cell changes. The source gNB sends a HANDOVER REQUEST / S-NODE Addition REQUEST message to the Candidate gNB, carrying one or more of the information from information a to information g:

[0392] Information a. UE's reference identifier at the source NG-RAN node (Source NG-RAN node UE XnAP ID reference);

[0393] Information b. First indication information, which is used to indicate that this LTM preparation involves / supports inter-CU LTM without key update or to indicate that this LTM preparation involves / supports inter-CU LTM cell change without changing PDCP node;

[0394] Information c. Second indication information, which indicates that the candidate gNB (i.e., the first candidate device mentioned above) is a PDCP anchor node. This second indication information only appears when the target candidate base station is the base station corresponding to the PDCP anchor node determined by the source base station, such as gNB#2 in the example above.

[0395] Information d. Node information of the PDCP anchor, wherein the node information of the PDCP anchor is used to indicate the node that can serve as the PDCP anchor in LTM cell changes, and the node information of the PDCP anchor includes one or more of the following:

[0396] gNB ID;

[0397] PLMN logo;

[0398] The UE's identifier under the PDCP anchor node is the UE XnAP ID;

[0399] Optionally, the node information of the PDCP anchor exists only when the candidate gNB is not a PDCP anchor node, i.e., it is the second candidate device mentioned above, used to indicate the PDCP anchor information corresponding to the DU under the candidate gNB in ​​this LTM preparation. For example, in the above example, the PDCP anchor information for gNB#1 is gNB#0; the PDCP anchor information for gNB#3 is gNB#3.

[0400] Information e. Association information, which includes the association relationship between the CU / gNB corresponding to the PDCP anchor / PDCP anchor and other candidate cells and / or the DU corresponding to the candidate cells and / or the CU / gNB corresponding to the candidate cells;

[0401] Each item in the associated information includes multiple node information, which is used to indicate that the UE does not need to perform a key update when moving between the cells corresponding to these node information during LTM cell switch.

[0402] The first / Nth item in the association information is the PDCP anchor, where N is defined by the protocol. For example, in the above example, the association information contains two items: the first item is {gNB#0, gNB#1}, and the second item is {gNB#2, gNB#3}.

[0403] Information f. PDU session related information, PDU Session Resources To Be Setup List.

[0404] Optionally, the node information of the PDCP anchor exists only when the candidate gNB is a PDCP anchor node, i.e., it is the first candidate device mentioned above; otherwise, this item does not exist. Alternatively, if this item is mandatory, the candidate gNB applies this item if it determines that it is a PDCP anchor; otherwise, this information is ignored.

[0405] Information g. Suggested DRB or SRB information, wherein the suggested DRB / SRB information is the DRB or SRB information suggested by the source node to be established by the PDCP anchor node. This includes information such as the DRB identifier or SRB identifier, and the mapping relationship between QoS flows and DRBs;

[0406] Optionally, this information exists only if the candidate gNB is a PDCP anchor node, i.e., the first candidate device mentioned above; otherwise, this information does not exist. Alternatively, if this information is mandatory, the candidate gNB will apply this information if it determines that it is a PDCP anchor; otherwise, this information will be ignored.

[0407] This information can be one or more copies. When it is one copy, all associated DUs of all PDCP anchors correspond to this information. When it is multiple copies, each PDCP anchor / candidate DU / candidate cell corresponds to one copy of this information, and each copy of this information contains its corresponding DU identifier / cell identifier.

[0408] Optionally, the source gNB and candidate gNB have one or more of the following capabilities:

[0409] Supports inter-CU LTM with keyless updates;

[0410] It supports one DU connecting to multiple CUs.

[0411] Optionally, before performing step 2, the source gNB has already obtained the aforementioned capability information of the candidate gNB.

[0412] If a candidate gNB / CU determines, based on the message sent by the source gNB, that it is not a PDCP anchor and that none of the candidate cells directly associated with it are its own PDCP anchors, then it becomes the second candidate device. This candidate gNB / CU does not generate CU-related configuration information and does not establish a UE context for the corresponding UE. It then sends a UE CONTEXT SETUP message to its directly associated candidate DU, optionally including the aforementioned first indication information.

[0413] Step 3. The Candidate gNB determines whether it is an anchor gNB based on the HANDOVER REQUEST message / S-NODE Addition REQUEST message from Step 2, and replies to the source gNB with a HANDOVER REQUEST ACKNOWLEDGE message / S-NODE Addition REQUEST ACKNOWLEDGE message. This HANDOVER REQUEST ACKNOWLEDGE message / S-NODE Addition REQUEST ACKNOWLEDGE message contains one or more of the following information a to h:

[0414] Information a.Source NG-RAN node UE XnAP ID;

[0415] Information b.. The UE's reference identifier at the target NG-RAN node (Target NG-RAN node UE XnAP ID);

[0416] Information c. Established DRB information. DRB or SRB information established by the PDCP anchor node, where each DRB corresponds to an uplink address (UL TNL Information) used to indicate the number of user plane transmission address information corresponding to the PDCP anchor node;

[0417] This information exists only if the candidate gNB is a PDCP anchor node; otherwise, this information does not exist; this information is generated by the CU of the candidate gNB.

[0418] This information can be one or more copies. When it is one copy, all DUs that share a PDCP anchor correspond to this information. When it is multiple copies, each candidate DU / candidate cell corresponds to one copy of this information, and each copy of this information contains its corresponding DU identifier / cell identifier.

[0419] The RRC configuration information generated by information d.CU includes DRB configuration information and / or key configuration information;

[0420] This information exists only if the candidate gNB is a PDCP anchor node, i.e., the first candidate device mentioned above; otherwise, this information does not exist.

[0421] This information can be one or more copies. When it is one copy, all DUs that share a PDCP anchor correspond to this information. When it is multiple copies, each candidate DU / candidate cell corresponds to one copy of this information, and each copy of this information contains its corresponding DU identifier / cell identifier.

[0422] Information e. The F1 interface identifier of the CU of the Candidate gNB corresponding to the PDCP anchor for the UE (gNB-CU UE F1AP ID);

[0423] This information exists only if the candidate gNB is a PDCP anchor node, i.e., it is the first candidate device mentioned above; otherwise, this information does not exist. This information is generated by the CU of the candidate gNB.

[0424] This information can be one or more copies. When it is one copy, all DUs that share a PDCP anchor correspond to this information. When it is multiple copies, each candidate DU / candidate cell corresponds to one copy of this information, and each copy of this information contains its corresponding DU identifier / cell identifier.

[0425] The DRB information list corresponding to information f.DU. The DRB information list corresponding to the DU is generated from the candidate DU, where each item corresponds to a DRB and contains downlink address information (DL TNL Information) to indicate the user plane transport address information corresponding to the candidate DU;

[0426] The aforementioned candidate DU stores the UE's RLC context. Each candidate cell corresponds to one such information. Optionally, if the DU is not directly connected to the PDCP anchor node (i.e., the first DU mentioned above), the DU generates this information based on the suggested DRB or SRB information in the HANDOVER REQUEST / S-NODE ADDITION REQUEST ACKNOWLEDGE message; otherwise, the DU generates this information based on the established DRB information generated by the PDCP anchor node, i.e., the second DU generates this information based on the established DRB information generated by the PDCP anchor node.

[0427] The RRC configuration information generated by g.DU includes cell group configuration information, which in turn includes RLC configuration information.

[0428] Each candidate cell corresponds to an RRC configuration information.

[0429] Optionally, if the DU is not a DU directly connected to the PDCP anchor node, i.e., the first DU mentioned above, the DU generates this information based on the suggested DRB or SRB information in the HANDOVER REQUEST message; otherwise, the DU generates this information based on the established DRB information generated by the PDCP anchor node.

[0430] Information h. The F1 interface identifier (gNB-DU UE F1AP ID) of the Candidate gNB corresponding to the non-PDCP anchor;

[0431] This information exists only when the candidate gNB is not a PDCP anchor node and its associated PDCP anchor is not the local base station, i.e., the aforementioned second candidate device.

[0432] It should be noted that the information f, information g, and information h mentioned above are the responses that the DU corresponding to the Candidate gNB receives from the CU via the UE CONTEXT SETUP REQUEST and then sends to the CU via the UE CONTEXT SETUP RESPONSE, which in turn sends to the source gNB.

[0433] Step 4. Switch to the preparation modification (HO preparation Modification), which includes two parts, as follows:

[0434] Part 1: Configuration updates for candidate DUs, including the following:

[0435] The source gNB sends the "established DRB information" generated by the PDCP anchor node in the received HANDOVER REQUEST ACKNOWLEDGE / S-NODE ADDITION REQUEST ACKNOWLEDGE message to other candidate gNBs (i.e., the second candidate device mentioned above) whose PDCP anchor is not the source node. This information includes a fourth indication and a candidate DU / candidate cell identifier. The fourth indication indicates that the information is an update of configuration information involving inter-CU LTM keyless update or that the information is directly passed through to the candidate DU (i.e., the first DU mentioned above). After receiving the message, the candidate gNB sends / passes through the information to the candidate DU.

[0436] The candidate DU updates the generated "DRB information corresponding to the DU" and "RRC configuration information generated by the DU" according to the "established DRB information" of its associated PDCP anchor, and sends the updated information to the associated CU, which then sends it to the Source gNB.

[0437] Part Two: Configuration Updates for the CU Corresponding to the PDCP Anchor, including the following:

[0438] The source gNB sends the RRC configuration information generated by the DU generated by the candidate gNB (i.e., the second candidate device mentioned above) that is not associated with the PDCP anchor to the PDCP anchor.

[0439] The gNB corresponding to the PDCP anchor (i.e., the first candidate device mentioned above) sends the updated "CU-generated RRC configuration information" to the Source gNB.

[0440] Step 5 (optional). The Source gNB sends a notification message (i.e., the first notification message mentioned above) to other Candiate gNBs to notify them of their corresponding address information.

[0441] When the Candidate gNB is a PDCP anchor node, the above notification message includes one or more of the following:

[0442] The F1 interface identifier (gNB-DU UE F1AP ID) of the Candidate gNB corresponding to the non-PDCP anchor for the UE.

[0443] First address information, which includes any of the following:

[0444] The list of "DRB information corresponding to DU" for all Candidate DUs associated with the PDCP anchor (one per DRB);

[0445] The list of "DRB information corresponding to DU" for Candidate DU (i.e. the first DU mentioned above) that is associated with the PDCP anchor but not directly connected to the PDCP anchor (one per DRB). The PDCP anchor and DU are not directly connected, that is, the gNB corresponding to the PDCP anchor and the gNB corresponding to the DU are not the same gNB.

[0446] The PDCP anchor is associated with a list of downlink address information for all Candidate DUs (i.e., the second DU mentioned above) (each DRB corresponds to one address), and each entry contains a DRB identifier and downlink address information;

[0447] Each item in the downlink address information (one address per DRB) corresponding to the Candidate DU associated with the PDCP anchor but not directly connected to the PDCP anchor contains a DRB identifier and a downlink address information.

[0448] When the Candidate gNB is not a PDCP anchor node, the above notification message (i.e., the second notification message above) includes one or more of the following:

[0449] The F1 interface identifier (gNB-CU UE F1AP ID) of the CU of the Candidate gNB corresponding to the PDCP anchor;

[0450] Second address information, which includes:

[0451] The list of uplink address information corresponding to the PDCP anchor associated with the Candidate gNB / DU (one address per DRB), each item in the list contains one DRB information and one uplink address information.

[0452] The source gNB sends the above notification information to the gNB corresponding to the candidate DU (i.e., the first DU mentioned above), which includes a fourth indication information and the candidate DU / candidate cell identifier. The fourth indication information is used to indicate that the information is related to the PDCP anchor address notification without key update of inter-CU LTM / the information is directly passed through to the candidate DU. After receiving the message, the candidate gNB sends / passes through the information to the candidate DU.

[0453] Through step 5, the CU corresponding to the PDCP anchor knows the F1-U DL TEID of the DU corresponding to the other base stations it is associated with, and the candidate DU also knows the F1-U UL TEID of the PDCP anchor of the other base stations it is associated with. In this way, the PDCP anchor can establish a user plane channel with the DU corresponding to the other base stations it is associated with. Data transmission can be directly transmitted between the candidate DU and the PDCP anchor without being forwarded by the candidate CU corresponding to the candidate DU. It can also avoid key updates when the UE moves between candidate cells corresponding to the same PDCP anchor, thereby reducing cell change latency.

[0454] Step 6. The Source gNB sends the LTM candidate configuration information to the UE.

[0455] Example 2:

[0456] This embodiment mainly describes the request by the gNB corresponding to the PDCP anchor (i.e., the first candidate device mentioned above) to its associated Candidate gNB (i.e., the second candidate device mentioned above). Specifically, it can be as follows:

[0457] The source gNB indicates to the gNB corresponding to the PDCP anchor that it is the PDCP anchor, and sends the identifiers of other candidate gNBs associated with it to that gNB;

[0458] The gNB corresponding to the PDCP anchor sends its F1-U UL address information to the DU of its associated other candidate gNBs (i.e., the first DU mentioned above), and requests the F1-U DL address information of the DU of its associated other candidate gNBs.

[0459] Other candidate gNBs will send the F1-U DL address information of the involved DU to the gNB corresponding to the associated PDCP anchor.

[0460] The specific process is shown in Figure 9, including the following steps:

[0461] Step 0.0. The UE is in an inactive state or a connected state (in RRC_INACTIVE CM-CONNECTED).

[0462] Step 1. The terminal performs measurement reporting.

[0463] Step 2a: The source gNB decides to perform LTM preparation. The source gNB decides to perform inter-CU LTM without key updates or to not change the PDCP node during inter-CU LTM cell changes. The source gNB determines the PDCP anchor and sends a first message to the first Candidate gNB (i.e., the aforementioned first candidate device) corresponding to the PDCP anchor. The first message is used to notify the PDCP anchor that it is the PDCP anchor for LTM preparation. The first message includes one or more of the following:

[0464] Source NG-RAN node UE XnAP ID reference;

[0465] The fifth indication information is used to indicate that the candidate gNB is a PDCP anchor node.

[0466] The candidate cell information associated with the PDCP anchor includes one or more of the following: candidate cell identifier (PCI), gNB ID corresponding to the candidate cell, DU ID corresponding to the candidate cell, PLMN identifier, PDU session-related information, and suggested DRB or SRB information.

[0467] The candidate cell information mentioned above is described in Example 1 above.

[0468] Optionally, the aforementioned source gNB and candidate gNB have one or more of the following capabilities:

[0469] Supports inter-CU LTM with keyless updates;

[0470] It supports one DU connecting to multiple CUs.

[0471] Optionally, before performing step 2, the source gNB has already obtained the aforementioned capability information of the candidate gNB.

[0472] Step 2b: Optionally, the first Candidate gNB sends a first response message to the source gNB to reply to the first message.

[0473] Step 3a: The first Candidate gNB corresponding to the PDCP anchor sends a third message to the DU (i.e., the first DU) corresponding to its associated other second Candidate gNBs (i.e., the aforementioned second candidate devices). This message may include a Partial UE CONTEXT SETUP REQUEST, used to request the establishment of a user plane data transmission channel with the DU. The third message includes one or more of the following:

[0474] The interface identifier of the UE is the Xn interface identifier of the UE in the first Candidate gNB and / or the F1 interface identifier of the CU in the first Candidate gNB (gNB-CU UE F1AP ID).

[0475] The sixth indication information is used to indicate that the first candidate gNB is used as a PDCP anchor node for the LTM preparation process.

[0476] Established DRB information. The DRB or SRB information established by the PDCP anchor node, where each DRB corresponds to an uplink address information (UL TNL Information), used to indicate the number of user plane transmission address information corresponding to the PDCP anchor node.

[0477] The first candidate gNB corresponding to the PDCP anchor sends a third message to the DU corresponding to other associated second candidate gNBs. This includes the first candidate gNB sending a third message and the candidate DU or candidate cell identifier to the CU corresponding to the second candidate gNB. The CU of the second candidate gNB sends / transmits the third message to the DU.

[0478] Step 3b: The second Candidate gNB sends a fourth message to the first Candidate gNB in ​​response to the third message. The fourth message includes one or more of the following:

[0479] The UE's interface identifier is the UE's Xn interface identifier in the second Candidate gNB and / or the F1 interface identifier in the second Candidate gNB's DU (gNB-DU UE F1AP ID).

[0480] The DRB information list corresponding to the DU. The DRB information list corresponding to the DU is generated from the candidate DU, where each item corresponds to a DRB and contains downlink address information (DL TNL Information) to indicate the user plane transport address information corresponding to the candidate DU;

[0481] The RRC configuration information generated by DU includes cell group configuration information, which in turn includes RLC configuration information.

[0482] The second Candidate gNB may be the same as or different from the first Candidate gNB.

[0483] The aforementioned fourth response message is generated by the DU of the second Candidate gNB and sent to the CU corresponding to the second Candidate gNB. The CU corresponding to the second Candidate gNB then sends the fourth message to the first Candidate gNB.

[0484] Through step 3, the CU corresponding to the PDCP anchor knows the F1-U DL TEID of the DU corresponding to the other base stations it is associated with, and the candidate DU also knows the F1-U UL TEID of the PDCP anchor of the other base stations it is associated with. In this way, the PDCP anchor can establish a user plane channel with the DU corresponding to the other base stations it is associated with, and data transmission can be directly transmitted between the candidate DU and the PDCP anchor without going through the forwarding of the candidate CU corresponding to the candidate DU.

[0485] Step 4. The first Candidate gNB sends a second message to the Source gNB, such as a Handover Modification Transfer, which includes LTM candidate configuration information. The LTM candidate configuration information includes configuration information of one or more candidate cells. The configuration information of each candidate cell includes CU-related configuration information generated by the first Candidate gNB corresponding to the PDCP anchor and DU-related configuration information generated by the second Candidate gNB corresponding to the candidate DU.

[0486] Optionally, before performing step 4, the Source gNB sends a request message to the first Candidate gNB for an LTM preparation request or LTM preparation modification.

[0487] Optionally, before performing step 4, the first Candidate gNB sends an indication message to the Source gNB, indicating that the CU corresponding to the PDCP anchor has obtained the information of the associated DU or has completed the establishment of a direct data plane transmission channel with the associated DU. The Source gNB sends the aforementioned request message to the first Candidate gNB only after receiving this indication message.

[0488] Through step 3, the PDCP anchor can obtain the complete configuration information of an LTM candidate cell, including the configuration information related to the CU and the configuration information related to its associated DU. Therefore, it can send the complete LTM candidate configuration information to the source gNB.

[0489] Step 5. The source gNB sends the LTM candidate configuration information to the UE.

[0490] The method provided in this application can maintain the PDCP node of the source base station. Specifically, it discloses how to determine the PDCP anchor and how to establish a data link channel between the PDCP anchor and the DU corresponding to other candidate base stations, thereby ensuring that no key update is performed during the inter-CU LTM process, reducing handover latency and complexity.

[0491] The information transmission method provided in this application can be executed by an information transmission device. This application uses an information transmission device executing the information transmission method as an example to illustrate the information transmission method apparatus provided in this application.

[0492] This application provides an information transmission device. As an example, the information transmission device may be a communication device or a component within a communication device, such as a chip. The communication device may be a network-side device or a server, etc. Exemplarily, the network-side device may include, but is not limited to, the types of network-side devices 12 listed above; this application does not impose specific limitations on these types.

[0493] The information transmission device includes a receiving module, a transmitting module, and a processing module. These modules can be implemented in software or hardware. When implemented in hardware, the processing module can be implemented by a processor. For example, the processor can include general-purpose processors, special-purpose processors, such as a Central Processing Unit (CPU), microprocessor, Digital Signal Processor (DSP), Artificial Intelligence (AI) processor, Graphics Processing Unit (GPU), Application Specific Integrated Circuit (ASIC), Network Processor (NP), Field Programmable Gate Array (FPGA), or other programmable logic devices, gate circuits, transistors, discrete hardware components, etc. The receiving and transmitting modules can be implemented by a communication interface, which can include one or more of the following: transceiver, pins, circuits, bus, radio frequency unit, etc.

[0494] Referring to Figure 10, when the information transmission device is a network-side device or a component within a network-side device, the information transmission device 1000 includes:

[0495] The sending module 1001 is configured to send first information to a first candidate device corresponding to a Packet Data Convergence Protocol anchor (PDCP), wherein the first information includes at least one of the following:

[0496] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0497] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0498] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0499] Optionally, the sending module 1001 is further configured to send second information to the second candidate device, the second information including:

[0500] The terminal's uplink address information on the PDCP anchor.

[0501] Optionally, the sending module of the device is configured to send a first request to the first candidate device, the first request including at least one of the following:

[0502] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0503] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0504] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0505] Protocol Data Unit (PDU) session information;

[0506] Data wirelessly carries DRB information;

[0507] Signaling radio bearer SRB information.

[0508] Optionally, the device further includes:

[0509] The receiving module is configured to receive a first response sent by the first candidate device, wherein the first response includes at least one of the following:

[0510] Established DRB information;

[0511] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0512] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0513] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0514] The DRB information of the second DU corresponding to the PDCP anchor.

[0515] Optionally, the content of the first response satisfies at least one of the following:

[0516] The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information;

[0517] The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information;

[0518] The DRB information of the second DU is generated based on the established DRB information;

[0519] The RRC configuration information generated by the second DU is generated based on the established DRB information.

[0520] Optionally, the sending module 1001 is further configured to send a second request to the second candidate device, the second request including at least one of the following:

[0521] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0522] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the PLMN identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0523] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0524] DRB information;

[0525] SRB information.

[0526] Optionally, the receiving module of the device is configured to receive a second response sent by the second candidate device, the second response including at least one of the following:

[0527] The RRC configuration information generated by the first DU;

[0528] The terminal is identified by the F1 interface of the first DU;

[0529] The DRB information of the first DU.

[0530] Optionally, the content of the second response satisfies at least one of the following:

[0531] The DRB information of the first DU is generated based on at least one of the DRB information and SRB information included in the second request;

[0532] The RRC configuration information generated by the first DU is generated based on at least one of the DRB information and SRB information included in the second request.

[0533] Optionally, the sending module of the device is configured to send a configuration update request to the second candidate device, the configuration update request including at least one of the following:

[0534] The second information;

[0535] Established DRB information;

[0536] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0537] The identification information of the first DU;

[0538] Identification information of candidate communities.

[0539] Optionally, the receiving module of the device is configured to receive a configuration update request response sent by the second candidate device, the configuration update request response including at least one of the following:

[0540] The DRB information updated by the first DU;

[0541] The first DU updates the RRC configuration information.

[0542] Optionally, the sending module 1001 is configured to send a first notification message to the first candidate device corresponding to the PDCP anchor, the first notification message including the first information, and further including at least one of the following:

[0543] The terminal is identified by the F1 interface of the first DU;

[0544] The DRB information of the first DU.

[0545] Optionally, the sending module 1001 is configured to send a second notification message to the second candidate device, the second notification message including the second information, and further including at least one of the following:

[0546] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0547] The DRB information of the PDCP anchor;

[0548] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0549] Optionally, the transmitting module of the device is configured to send a first message to the first candidate device corresponding to the PDCP anchor, the first message including relevant information of the second candidate device, and further including at least one of the following:

[0550] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0551] PDU session information;

[0552] DRB information;

[0553] SRB information.

[0554] Optionally, the receiving module of the device is configured to receive a second message sent by the first candidate device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0555] Configuration information related to the CU of the first candidate device;

[0556] Configuration information related to the DU of the second candidate device.

[0557] Optionally, the sending module 1001 is further configured to send a serving cell change preparation request or a serving cell change preparation modification request to the first candidate device.

[0558] Optionally, the receiving module of the device is configured to receive indication information sent by the first candidate device, the indication information being used to indicate at least one of the following:

[0559] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0560] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0561] Optionally, the receiving module of the device is configured to acquire capability information of at least one of the first candidate device and the second candidate device, wherein the capability information represents at least one of the following:

[0562] Supports keyless update for serving cell changes between CUs;

[0563] It supports one DU connecting to multiple CUs.

[0564] The aforementioned information transmission device can reduce cell change latency.

[0565] The information transmission device provided in this application embodiment can implement the various processes implemented in the method embodiment of FIG3 and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0566] Referring to Figure 11, when the information transmission device is a network-side device or a component within a network-side device, the information transmission device 1100 includes:

[0567] The receiving module 1101 is used to receive first information sent by the source device, wherein the device corresponding to the device is the device corresponding to the Packet Data Convergence Protocol anchor (PDCP anchor), and the first information includes at least one of the following:

[0568] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0569] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0570] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0571] Optionally, the receiving module 1001 is further configured to receive a first request sent by the source device, the first request including at least one of the following:

[0572] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0573] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0574] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0575] Protocol Data Unit (PDU) session information;

[0576] Data wirelessly carries DRB information;

[0577] Signaling radio bearer SRB information.

[0578] Optionally, the device further includes:

[0579] The sending module is configured to send a first response to the source device, the first response including at least one of the following:

[0580] Established DRB information;

[0581] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0582] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0583] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0584] The DRB information of the second DU corresponding to the PDCP anchor.

[0585] Optionally, the content of the first response satisfies at least one of the following:

[0586] The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information;

[0587] The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information;

[0588] The DRB information of the second DU is generated based on the established DRB information;

[0589] The RRC configuration information generated by the second DU is generated based on the established DRB information.

[0590] Optionally, the receiving module 1001 is configured to receive a first notification message sent by the source device, the first notification message including the first information, and further including at least one of the following:

[0591] The terminal is identified by the F1 interface of the first DU;

[0592] The DRB information of the first DU.

[0593] Optionally, the first candidate device receives first information sent by the source device, including:

[0594] The first candidate device receives a first message sent by the source device, the first message including the identification information of the second candidate device, and also including at least one of the following:

[0595] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0596] PDU session information;

[0597] DRB information;

[0598] SRB information.

[0599] Optionally, the sending module of the device is configured to send a third message to the second candidate device, the third message being used to request the establishment of a user plane data transmission channel with the first DU.

[0600] Optionally, the third message includes at least one of the following:

[0601] The terminal is identified by the Xn interface of the first candidate device;

[0602] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0603] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0604] Established DRB information;

[0605] The terminal's uplink address information at the PDCP anchor;

[0606] The identification information of the first DU;

[0607] The identification information of the candidate cell associated with the PDCP anchor.

[0608] Optionally, the receiving module 1001 is further configured to receive a fourth message sent by the second candidate device, the fourth message including at least one of the following:

[0609] The terminal is identified by the Xn interface of the second candidate device;

[0610] The terminal is identified by the F1 interface of the first DU;

[0611] DRB information of the first DU;

[0612] The terminal's downlink address information in the first DU;

[0613] The RRC configuration information of the first DU.

[0614] Optionally, the sending module of the device is configured to send a second message to the source device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0615] Configuration information related to the CU of the first candidate device;

[0616] Configuration information related to the DU of the second candidate device.

[0617] Optionally, the receiving module 1001 is further configured to receive a serving cell change preparation request or a serving cell change preparation modification request sent by the source device.

[0618] Optionally, the transmitting module of the device is configured to send indication information to the source device, the indication information indicating at least one of the following:

[0619] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0620] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0621] Optionally, the transmitting module of the device is used to transmit capability information to the source device, the capability information representing at least one of the following:

[0622] Supports keyless update for serving cell changes between CUs;

[0623] It supports one DU connecting to multiple CUs.

[0624] The aforementioned information transmission device can reduce cell change latency.

[0625] The information transmission device provided in this application embodiment can implement the various processes implemented in the method embodiment of FIG5 and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0626] Referring to Figure 12, when the information transmission device is a network-side device or a component within a network-side device, the information transmission device 1200 includes:

[0627] The receiving module 1201 is used to receive the uplink address information of the terminal at the Packet Data Convergence Protocol anchor (PDCP).

[0628] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0629] Optionally, the receiving module 1201 is used to receive second information sent by the source device, the second information including:

[0630] The terminal's uplink address information on the PDCP anchor.

[0631] Optionally, the receiving module 1201 is further configured to receive a second request sent by the source device, the second request including at least one of the following:

[0632] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0633] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the Public Land Mobile Network (PLMN) identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0634] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0635] DRB information;

[0636] SRB information.

[0637] Optionally, the device further includes:

[0638] The sending module is configured to send a second response to the source device, the second response including at least one of the following:

[0639] The RRC configuration information generated by the first DU;

[0640] The terminal is identified by the F1 interface of the first DU;

[0641] The DRB information of the first DU.

[0642] Optionally, the receiving module 1201 is further configured to receive a configuration update request sent by the source device, the configuration update request including at least one of the following:

[0643] The second information;

[0644] Established DRB information;

[0645] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0646] The identification information of the first DU;

[0647] Identification information of candidate communities.

[0648] Optionally, the receiving module 1201 is configured to receive a second notification message sent by the source device, the second notification message including the uplink address information of the terminal at the PDCP anchor, and further including at least one of the following:

[0649] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0650] The DRB information of the PDCP anchor;

[0651] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0652] Optionally, the receiving module 1201 is configured to receive a third message sent by the first candidate device, the third message being used to request the establishment of a user plane data transmission channel with the first DU, and the third message including the uplink address information of the terminal at the PDCP anchor.

[0653] Optionally, the third message further includes at least one of the following:

[0654] The terminal is identified by the Xn interface of the first candidate device;

[0655] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0656] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0657] Established DRB information;

[0658] The identification information of the first DU;

[0659] The identification information of the candidate cell associated with the PDCP anchor.

[0660] Optionally, the sending module of the device is configured to send a fourth message to the first candidate device, the fourth message including at least one of the following:

[0661] The terminal is identified by the Xn interface of the second candidate device;

[0662] The terminal is identified by the F1 interface of the first DU;

[0663] DRB information of the first DU;

[0664] The terminal's downlink address information in the first DU;

[0665] The RRC configuration information of the first DU.

[0666] Optionally, the transmitting module of the device is used to transmit capability information to the source device, the capability information representing at least one of the following:

[0667] Supports keyless update for serving cell changes between CUs;

[0668] It supports one DU connecting to multiple CUs.

[0669] The aforementioned information transmission device can reduce cell change latency.

[0670] The information transmission device provided in this application embodiment can implement the various processes implemented in the method embodiment of FIG6 and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0671] As shown in Figure 13, this application embodiment also provides a communication device 1300, including a processor 1301 and a memory 1302. The memory 1302 stores a program or instructions that can run on the processor 1301. For example, when the communication device 1300 is a terminal, the program or instructions executed by the processor 1301 implement the various steps of the above-described information transmission method embodiment and achieve the same technical effect. When the communication device 1300 is a network-side device, the program or instructions executed by the processor 1301 implement the various steps of the above-described information transmission method embodiment and achieve the same technical effect. To avoid repetition, this will not be described again here.

[0672] This application also provides a network-side device, including a processor and a communication interface. The communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the steps of the method embodiments shown in FIG3, FIG5, or FIG6. This network-side device embodiment corresponds to the above-described network-side device method embodiments. All implementation processes and methods of the above-described method embodiments can be applied to this network-side device embodiment and can achieve the same technical effects.

[0673] Specifically, this application embodiment also provides a network-side device, which may be the information transmission device shown in FIG10, FIG11, or FIG12. As shown in FIG14, the network-side device 1400 includes: an antenna 141, a radio frequency device 142, a baseband device 143, a processor 144, and a memory 145. The antenna 141 is connected to the radio frequency device 142. In the uplink direction, the radio frequency device 142 receives information through the antenna 141 and sends the received information to the baseband device 143 for processing. In the downlink direction, the baseband device 143 processes the information to be transmitted and sends it to the radio frequency device 142. The radio frequency device 142 processes the received information and transmits it through the antenna 141.

[0674] The method executed by the network-side device in the above embodiments can be implemented in the baseband device 143, which includes a baseband processor.

[0675] The baseband device 143 may include at least one baseband board, on which multiple chips are disposed, as shown in FIG14. One of the chips is, for example, a baseband processor, which is connected to the memory 145 via a bus interface to call the program in the memory 145 and execute the network device operation shown in the above method embodiment.

[0676] The network-side device may also include a network interface 146, such as a Common Public Radio Interface (CPRI).

[0677] Specifically, the network-side device 1400 in this application embodiment further includes: instructions or programs stored in memory 145 and executable on processor 144. The processor 144 calls the instructions or programs in memory 145 to execute the methods executed by the modules shown in FIG10, FIG11 or FIG12 and achieve the same technical effect. To avoid repetition, it will not be described in detail here.

[0678] In the above embodiment where the network-side device is the source device:

[0679] Radio frequency device 142 is configured to send first information to a first candidate device corresponding to a Packet Data Convergence Protocol anchor (PDCP), the first information including at least one of the following:

[0680] The terminal's downlink address information of the first distribution unit (DU) associated with the PDCP anchor;

[0681] The relevant information of the second candidate device associated with the PDCP anchor includes at least one of the following: the cell identifier of the candidate cell of the second candidate device; the Xn identifier information of the second candidate device; the identifier information of the first DU; and the public land mobile network (PLMN) of the candidate cell of the second candidate device.

[0682] Wherein, the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

[0683] Optionally, the radio frequency device 142 is further configured to send second information to the second candidate device, the second information including:

[0684] The terminal's uplink address information on the PDCP anchor.

[0685] Optionally, the radio frequency device 142 is further configured to send a first request to the first candidate device, the first request including at least one of the following:

[0686] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0687] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0688] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0689] Protocol Data Unit (PDU) session information;

[0690] Data wirelessly carries DRB information;

[0691] Signaling radio bearer SRB information.

[0692] Optionally, the radio frequency device 142 is further configured to receive a first response sent by the first candidate device, the first response including at least one of the following:

[0693] Established DRB information;

[0694] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0695] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0696] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0697] The DRB information of the second DU corresponding to the PDCP anchor.

[0698] Optionally, the content of the first response satisfies at least one of the following:

[0699] The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information;

[0700] The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information;

[0701] The DRB information of the second DU is generated based on the established DRB information;

[0702] The RRC configuration information generated by the second DU is generated based on the established DRB information.

[0703] Optionally, the radio frequency device 142 is further configured to send a second request to the second candidate device, the second request including at least one of the following:

[0704] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0705] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the PLMN identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0706] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0707] DRB information;

[0708] SRB information.

[0709] Optionally, the radio frequency device 142 is further configured to receive a second response sent by the second candidate device, the second response including at least one of the following:

[0710] The RRC configuration information generated by the first DU;

[0711] The terminal is identified by the F1 interface of the first DU;

[0712] The DRB information of the first DU.

[0713] Optionally, the content of the second response satisfies at least one of the following:

[0714] The DRB information of the first DU is generated based on at least one of the DRB information and SRB information included in the second request;

[0715] The RRC configuration information generated by the first DU is generated based on at least one of the DRB information and SRB information included in the second request.

[0716] Optionally, the radio frequency device 142 is further configured to send a configuration update request to the second candidate device, the configuration update request including at least one of the following:

[0717] The second information;

[0718] Established DRB information;

[0719] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0720] The identification information of the first DU;

[0721] Identification information of candidate communities.

[0722] Optionally, the radio frequency device 142 is further configured to receive a configuration update request response sent by the second candidate device, the configuration update request response including at least one of the following:

[0723] The DRB information updated by the first DU;

[0724] The first DU updates the RRC configuration information.

[0725] Optionally, sending the first information to the first candidate device corresponding to the PDCP anchor includes:

[0726] Send a first notification message to the first candidate device corresponding to the PDCP anchor. The first notification message includes the first information and also includes at least one of the following:

[0727] The terminal is identified by the F1 interface of the first DU;

[0728] The DRB information of the first DU.

[0729] Optionally, sending the second information to the second candidate device includes:

[0730] Send a second notification message to the second candidate device, the second notification message including the second information, and further including at least one of the following:

[0731] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0732] The DRB information of the PDCP anchor;

[0733] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0734] Optionally, sending the first information to the first candidate device corresponding to the PDCP anchor includes:

[0735] Send a first message to the first candidate device corresponding to the PDCP anchor, the first message including relevant information about the second candidate device, and also including at least one of the following:

[0736] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0737] PDU session information;

[0738] DRB information;

[0739] SRB information.

[0740] Optionally, the radio frequency device 142 is further configured to receive a second message sent by the first candidate device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0741] Configuration information related to the CU of the first candidate device;

[0742] Configuration information related to the DU of the second candidate device.

[0743] Optionally, the radio frequency device 142 is further configured to send a serving cell change preparation request or a serving cell change preparation modification request to the first candidate device.

[0744] Optionally, before sending a serving cell change preparation request or a serving cell change preparation modification request to the first candidate device, the radio frequency device 142 is further configured to:

[0745] Receive indication information sent by the first candidate device, the indication information being used to indicate at least one of the following:

[0746] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0747] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0748] Optionally, the radio frequency device 142 is further configured to acquire capability information of at least one of the first candidate device and the second candidate device, the capability information representing at least one of the following:

[0749] Supports keyless update for serving cell changes between CUs;

[0750] It supports one DU connecting to multiple CUs.

[0751] In the embodiment where the network-side device is the first candidate device:

[0752] Radio frequency device 142 is used to receive uplink address information of the terminal at the Packet Data Convergence Protocol anchor (PDCP).

[0753] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0754] Optionally, the radio frequency device 142 is further configured to receive a first request sent by the source device, the first request including at least one of the following:

[0755] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0756] The second indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor.

[0757] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0758] Protocol Data Unit (PDU) session information;

[0759] Data wirelessly carries DRB information;

[0760] Signaling radio bearer SRB information.

[0761] Optionally, the radio frequency device 142 is further configured to send a first response to the source device, the first response including at least one of the following:

[0762] Established DRB information;

[0763] The RRC configuration information generated by the CU corresponding to the PDCP anchor;

[0764] The RRC configuration information generated by the second DU corresponding to the PDCP anchor;

[0765] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0766] The DRB information of the second DU corresponding to the PDCP anchor.

[0767] Optionally, the content of the first response satisfies at least one of the following:

[0768] The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information and key configuration information;

[0769] The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes: cell group configuration information;

[0770] The DRB information of the second DU is generated based on the established DRB information;

[0771] The RRC configuration information generated by the second DU is generated based on the established DRB information.

[0772] Optionally, receiving the first information sent by the source device includes:

[0773] The system receives a first notification message sent by the source device, the first notification message including the first information, and further including at least one of the following:

[0774] The terminal is identified by the F1 interface of the first DU;

[0775] The DRB information of the first DU.

[0776] Optionally, the first information sent by the receiving source device includes:

[0777] The device receives a first message sent by the source device, the first message including the identification information of the second candidate device, and also including at least one of the following:

[0778] The fifth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0779] PDU session information;

[0780] DRB information;

[0781] SRB information.

[0782] Optionally, the radio frequency device 142 is further configured to send a third message to the second candidate device, the third message being used to request the establishment of a user plane data transmission channel with the first DU.

[0783] Optionally, the third message includes at least one of the following:

[0784] The terminal is identified by the Xn interface of the first candidate device;

[0785] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0786] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0787] Established DRB information;

[0788] The terminal's uplink address information at the PDCP anchor;

[0789] The identification information of the first DU;

[0790] The identification information of the candidate cell associated with the PDCP anchor.

[0791] Optionally, the radio frequency device 142 is further configured to receive a fourth message sent by the second candidate device, the fourth message including at least one of the following:

[0792] The terminal is identified by the Xn interface of the second candidate device;

[0793] The terminal is identified by the F1 interface of the first DU;

[0794] DRB information of the first DU;

[0795] The terminal's downlink address information in the first DU;

[0796] The RRC configuration information of the first DU.

[0797] Optionally, the radio frequency device 142 is further configured to send a second message to the source device, the second message including serving cell change candidate configuration information, the serving cell change candidate configuration information including at least one of the following:

[0798] Configuration information related to the CU of the first candidate device;

[0799] Configuration information related to the DU of the second candidate device.

[0800] Optionally, the radio frequency device 142 is further configured to receive a serving cell change preparation request or a serving cell change preparation modification request sent by the source device.

[0801] Optionally, before receiving the serving cell change preparation request or serving cell change preparation modification request sent by the source device, the radio frequency device 142 is further configured to:

[0802] Send indication information to the source device, the indication information being used to indicate at least one of the following:

[0803] The CU corresponding to the PDCP anchor has already obtained the information of the first DU;

[0804] The CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

[0805] Optionally, the radio frequency device 142 is further configured to send capability information to the source device, the capability information representing at least one of the following:

[0806] Supports keyless update for serving cell changes between CUs;

[0807] It supports one DU connecting to multiple CUs.

[0808] In the embodiment where the network-side device is the second candidate device:

[0809] Radio frequency device 142 is used to receive uplink address information of the terminal at the Packet Data Convergence Protocol anchor (PDCP).

[0810] The second candidate device is different from the first candidate device corresponding to the PDCP anchor, and the first DU corresponding to the second candidate device is the DU associated with the PDCP anchor.

[0811] Optionally, the uplink address information of the receiving terminal at the PDCP anchor includes:

[0812] Receive second information sent by the source device, the second information including:

[0813] The terminal's uplink address information on the PDCP anchor.

[0814] Optionally, the radio frequency device 142 is further configured to receive a second request sent by the source device, the second request including at least one of the following:

[0815] The first instruction information is used to indicate that the serving cell change preparation process is the preparation for serving cell change between centralized units (CUs). The serving cell change between CUs supports not updating the key, or the serving cell change between CUs supports not involving PDCP anchor change.

[0816] The PDCP anchor information includes at least one of the following: the identification information of the first candidate device, the Public Land Mobile Network (PLMN) identifier, and the identification information of the terminal at the Xn interface of the PDCP anchor;

[0817] Association information, which indicates at least one of the following: the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the second candidate device; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the CU of the candidate cell associated with the PDCP anchor; the association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU;

[0818] DRB information;

[0819] SRB information.

[0820] Optionally, the radio frequency device 142 is further configured to send a second response to the source device, the second response including at least one of the following:

[0821] The RRC configuration information generated by the first DU;

[0822] The terminal is identified by the F1 interface of the first DU;

[0823] The DRB information of the first DU.

[0824] Optionally, the radio frequency device 142 is further configured to receive a configuration update request sent by the source device, the configuration update request including at least one of the following:

[0825] The second information;

[0826] Established DRB information;

[0827] The third indication information is used to indicate that the configuration update request involves a keyless configuration update between CUs, or the third indication information is used to indicate that it is passed through to the first DU;

[0828] The identification information of the first DU;

[0829] Identification information of candidate communities.

[0830] Optionally, the uplink address information of the receiving terminal at the PDCP anchor includes:

[0831] The terminal receives a second notification message sent by the source device, the second notification message including the uplink address information of the terminal at the PDCP anchor, and also including at least one of the following:

[0832] The terminal is identified by the F1 interface of the CU corresponding to the PDCP anchor;

[0833] The DRB information of the PDCP anchor;

[0834] The fourth indication information is used to indicate that the second notification message involves a keyless PDCP anchor information notification for a change in serving cell between CUs, or the fourth indication information is used to indicate that it is transparently transmitted to the first DU.

[0835] Optionally, the uplink address information of the receiving terminal at the PDCP anchor includes:

[0836] The terminal receives a third message sent by the first candidate device. The third message is used to request the establishment of a user plane data transmission channel with the first DU, and the third message includes the uplink address information of the terminal at the PDCP anchor.

[0837] Optionally, the third message further includes at least one of the following:

[0838] The terminal is identified by the Xn interface of the first candidate device;

[0839] The terminal is identified by the F1 interface of the CU in the first candidate device;

[0840] The sixth indication information is used to indicate that the first candidate device is the device corresponding to the PDCP anchor;

[0841] Established DRB information;

[0842] The identification information of the first DU;

[0843] The identification information of the candidate cell associated with the PDCP anchor.

[0844] Optionally, the radio frequency device 142 is further configured to send a fourth message to the first candidate device, the fourth message including at least one of the following:

[0845] The terminal is identified by the Xn interface of the second candidate device;

[0846] The terminal is identified by the F1 interface of the first DU;

[0847] DRB information of the first DU;

[0848] The terminal's downlink address information in the first DU;

[0849] The RRC configuration information of the first DU.

[0850] Optionally, the radio frequency device 142 is further configured to send capability information to the source device, the capability information representing at least one of the following:

[0851] Supports keyless update for serving cell changes between CUs;

[0852] It supports one DU connecting to multiple CUs.

[0853] The aforementioned network-side equipment can reduce cell change latency.

[0854] The information transmission device provided in this application embodiment can implement the various processes implemented in the method embodiments of FIG3, FIG5 or FIG6, and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0855] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described information transmission method embodiments and achieve the same technical effects. To avoid repetition, they will not be described again here.

[0856] The processor mentioned above is the processor in the terminal described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk. In some examples, the readable storage medium may be a non-transient readable storage medium.

[0857] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the above-described information transmission method embodiments and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0858] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0859] This application also provides a computer program / program product, which is stored in a storage medium and executed by at least one processor to implement the various processes of the above-described information transmission method embodiments, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0860] This application also provides a source device, a first candidate device, and a second candidate device. The source device can be used to perform the steps of the method of the source device provided in this application. The first candidate device can be used to perform the steps of the method of the first candidate device provided in this application. The second candidate device can be used to perform the steps of the method of the second candidate device provided in this application.

[0861] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0862] From the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of computer software products plus necessary general-purpose hardware platforms, and of course, they can also be implemented by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.) and includes several instructions to cause the terminal or network-side device to execute the methods described in the various embodiments of this application.

[0863] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other implementations under the guidance of this application without departing from the spirit and scope of the claims. All of these implementations are within the protection scope of this application.

Claims

1. A method for information transmission, comprising: sending, by a source device, first information to a first candidate device corresponding to a packet data convergence protocol (PDCP) anchor, the first information comprising at least one of: downlink address information of a first distributed unit (DU) associated with the PDCP anchor; related information of a second candidate device associated with the PDCP anchor, the related information comprising at least one of: a cell identity of a candidate cell of the second candidate device; Xn identification information of the second candidate device; identification information of the first DU; a public land mobile network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

2. The method of claim 1, further comprising: sending, by the source device, second information to the second candidate device, the second information comprising: uplink address information of the terminal at the PDCP anchor.

3. The method of claim 1 or 2, further comprising: sending, by the source device, a first request to the first candidate device, the first request comprising at least one of: first indication information indicating that a service cell change preparation procedure is preparation for a centralized unit (CU)-inter-cell service cell change, the CU-inter-cell service cell change supporting no key update, or the CU-inter-cell service cell change supporting no PDCP anchor change; second indication information indicating that the first candidate device is a device corresponding to the PDCP anchor; association information indicating at least one of: an association relationship between the first candidate device or the PDCP anchor or a CU corresponding to the PDCP anchor and the second candidate device; an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and a CU of a candidate cell associated with the PDCP anchor; an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; protocol data unit (PDU) session information; data radio bearer (DRB) information; signaling radio bearer (SRB) information.

4. The method of claim 3, further comprising: receiving, by the source device, a first response sent by the first candidate device, the first response comprising at least one of: established DRB information; RRC configuration information generated by a CU corresponding to the PDCP anchor; RRC configuration information generated by a second DU corresponding to the PDCP anchor; F1 interface identification of the CU corresponding to the PDCP anchor; DRB information of the second DU corresponding to the PDCP anchor.

5. The method of claim 4, wherein, the content included in the first response satisfies at least one of: The RRC configuration information generated by the CU corresponding to the PDCP anchor comprises at least one of DRB configuration information and key configuration information; The RRC configuration information generated by the second DU corresponding to the PDCP anchor comprises cell group configuration information; The DRB information of the second DU is generated based on the established DRB information; The RRC configuration information generated by the second DU is generated based on the established DRB information.

6. The method of any one of claims 1-5, further comprising: sending, by the source device, a second request to the second candidate device, the second request comprising at least one of: first indication information indicating that the service cell change preparation procedure is preparation for a centralized unit (CU)-inter-cell service change, the CU-inter-cell service change supporting no key update or the CU-inter-cell service change supporting no PDCP anchor change; information of the PDCP anchor comprising at least one of identification information of the first candidate device, a PLMN identifier, and identification information of the terminal on an Xn interface of the PDCP anchor; association information indicating at least one of an association relationship between the first candidate device or the PDCP anchor or a CU corresponding to the PDCP anchor and the second candidate device, an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and a CU of a candidate cell associated with the PDCP anchor, and an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; DRB information; and SRB information.

7. The method of claim 6, further comprising: receiving, by the source device, a second response sent by the second candidate device, the second response comprising at least one of: RRC configuration information generated by the first DU; an F1 interface identifier of the terminal on the first DU; DRB information of the first DU.

8. The method of claim 7, wherein, The content included in the second response satisfies at least one of: the DRB information of the first DU is generated based on at least one of the DRB information and the SRB information included in the second request; the RRC configuration information generated by the first DU is generated based on at least one of the DRB information and the SRB information included in the second request.

9. The method of any one of claims 2-8, comprising: sending, by the source device, a configuration update request to the second candidate device, the configuration update request comprising at least one of: the second information; established DRB information; third indication information indicating that the configuration update request involves a CU-inter-cell configuration update without a key, or the third indication information indicating a pass-through to the first DU. identification information of the first DU; identification information of the candidate cell. 10.The method of claim 9, further comprising: receiving, by the source device, a configuration update request response sent by the second candidate device, the configuration update request response comprising at least one of: DRB information updated by the first DU; RRC configuration information updated by the first DU.

11. The method of any one of claims 1 to 10, wherein, sending, by the source device, the first information to the first candidate device corresponding to the PDCP anchor comprises: sending, by the source device, a first notification message to the first candidate device corresponding to the PDCP anchor, the first notification message comprising the first information and further comprising at least one of: F1 interface identification of the first DU by the terminal; DRB information of the first DU.

12. The method of any one of claims 2 to 11, wherein, sending, by the source device, the second information to the second candidate device comprises: sending, by the source device, a second notification message to the second candidate device, the second notification message comprising the second information and further comprising at least one of: F1 interface identification of the CU corresponding to the PDCP anchor by the terminal; DRB information of the PDCP anchor; fourth indication information, the fourth indication information being used to indicate that the second notification message is related to inter-CU service cell change no-key PDCP anchor information notification or the fourth indication information is used to indicate that the first DU is transparently transmitted.

13. The method of claim 1, wherein, sending, by the source device, the first information to the first candidate device corresponding to the PDCP anchor comprises: sending, by the source device, a first message to the first candidate device corresponding to the PDCP anchor, the first message comprising related information of the second candidate device and further comprising at least one of: fifth indication information, the fifth indication information being used to indicate that the first candidate device is a device corresponding to the PDCP anchor; PDU session information; DRB information; SRB information. 14.The method of claim 1 or 13, further comprising: receiving, by the source device, a second message sent by the first candidate device, the second message comprising service cell change candidate configuration information, the service cell change candidate configuration information comprising at least one of: CU related configuration information of the first candidate device; DU related configuration information of the second candidate device. 15.The method of claim 13 or 14, further comprising: sending, by the source device, a service cell change preparation request or a service cell change preparation modification request to the first candidate device.

16. The method of claim 15, wherein, Before the source device sends the service cell change preparation request or the service cell change preparation modification request to the first candidate device, the method further comprises: receiving, by the source device, indication information sent by the first candidate device, the indication information being used to indicate at least one of: the CU corresponding to the PDCP anchor has acquired information of the first DU; the CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

17. The method of any of claims 1-16, further comprising: the source device obtaining capability information of at least one of the first candidate device and the second candidate device, the capability information indicating at least one of: support of a service cell change between CUs without key update; support of one DU connecting multiple CUs.

18. A method of information transmission, comprising: a first candidate device receiving first information sent by a source device, the first candidate device being a device corresponding to a packet data convergence protocol anchor (PDCP anchor), the first information comprising at least one of: downlink address information of a first distributed unit (DU) associated with the PDCP anchor for a terminal; related information of a second candidate device associated with the PDCP anchor, the related information comprising at least one of: a cell identifier of a candidate cell of the second candidate device; Xn identification information of the second candidate device; identification information of the first DU; a public land mobile network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

19. The method of claim 18, further comprising: the first candidate device receiving a first request sent by the source device, the first request comprising at least one of: first indication information indicating that a service cell change preparation procedure is preparation for a service cell change between centralized units (CUs), the service cell change between CUs supporting no key update, or the service cell change between CUs supporting no PDCP anchor change; second indication information indicating that the first candidate device is a device corresponding to a PDCP anchor; association information indicating at least one of: an association relationship between the first candidate device or the PDCP anchor or a CU corresponding to the PDCP anchor and the second candidate device; an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and a CU of a candidate cell associated with the PDCP anchor; an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; protocol data unit (PDU) session information; data radio bearer (DRB) information; signaling radio bearer (SRB) information.

20. The method of claim 19, further comprising: the first candidate device sending a first response to the source device, the first response comprising at least one of: established DRB information; RRC configuration information generated by a CU corresponding to the PDCP anchor; RRC configuration information generated by a second DU corresponding to the PDCP anchor; an F1 interface identifier of the CU corresponding to the PDCP anchor for the terminal. DRB information of the second DU corresponding to the PDCP anchor.

21. The method of claim 20, wherein, The content included in the first response satisfies at least one of the following: The RRC configuration information generated by the CU corresponding to the PDCP anchor includes at least one of the following: DRB configuration information, key configuration information; The RRC configuration information generated by the second DU corresponding to the PDCP anchor includes cell group configuration information; The DRB information of the second DU is generated based on the established DRB information; The RRC configuration information generated by the second DU is generated based on the established DRB information.

22. The method of any one of claims 18-21, wherein, The first candidate device receives the first information sent by the source device, including: The first candidate device receives the first notification message sent by the source device, and the first notification message includes the first information and further includes at least one of the following: The terminal is identified at the F1 interface of the first DU; The DRB information of the first DU.

23. The method of claim 18, wherein, The first candidate device receives the first information sent by the source device, including: The first candidate device receives the first message sent by the source device, and the first message includes the identification information of the second candidate device and further includes at least one of the following: Fifth indication information, the fifth indication information is used to indicate that the first candidate device is a device corresponding to the PDCP anchor; PDU session information; DRB information; SRB information.

24. The method of claim 23, further comprising: The first candidate device sends a third message to the second candidate device, and the third message is used to request to establish a user plane data transmission channel with the first DU.

25. The method of claim 24, wherein, The third message includes at least one of the following: The terminal is identified at the Xn interface of the first candidate device; The terminal is identified at the F1 interface of the CU of the first candidate device; Sixth indication information, the sixth indication information is used to indicate that the first candidate device is a device corresponding to the PDCP anchor; Established DRB information; The uplink address information of the terminal at the PDCP anchor; Identification information of the first DU; Identification information of the candidate cell associated with the PDCP anchor.

26. The method of claim 24 or 25, further comprising: The first candidate device receives the fourth message sent by the second candidate device, and the fourth message includes at least one of the following: The terminal is identified at the Xn interface of the second candidate device; The terminal is identified at the F1 interface of the first DU; The DRB information of the first DU; The downlink address information of the terminal at the first DU; The RRC configuration information of the first DU.

27. The method of any one of claims 23 to 26, further comprising: The first candidate device sends a second message to the source device, and the second message includes service cell change candidate configuration information, and the service cell change candidate configuration information includes at least one of the following: The CU-related configuration information of the first candidate device; The DU-related configuration information of the second candidate device.

28. The method of any of claims 23-27, further comprising: receiving, by the first candidate device, a serving cell change preparation request or a serving cell change preparation modification request sent by the source device.

29. The method of claim 28, wherein, Before the first candidate device receives the serving cell change preparation request or the serving cell change preparation modification request sent by the source device, the method further comprises: sending, by the first candidate device, indication information to the source device, the indication information indicating at least one of: the CU corresponding to the PDCP anchor has acquired information of the first DU; the CU corresponding to the PDCP anchor has established a data plane transmission channel with the first DU.

30. The method of any of claims 18-29, further comprising: sending, by the first candidate device, capability information to the source device, the capability information indicating at least one of: supporting serving cell change between CUs without key update; supporting one DU connecting multiple CUs.

31. An information transmission method, comprising: receiving, by a second candidate device, uplink address information of a terminal at a packet data convergence protocol anchor (PDCP anchor); wherein the second candidate device is different from a first candidate device corresponding to the PDCP anchor, and a first DU corresponding to the second candidate device is a DU associated with the PDCP anchor.

32. The method of claim 31, wherein, receiving, by the second candidate device, the uplink address information of the terminal at the PDCP anchor comprises: receiving, by the second candidate device, second information sent by a source device, the second information comprising: the uplink address information of the terminal at the PDCP anchor.

33. The method of claim 32, further comprising: receiving, by the second candidate device, a second request sent by the source device, the second request comprising at least one of: first indication information indicating that a serving cell change preparation procedure is preparation for serving cell change between CUs, the serving cell change between CUs supporting no key update or the serving cell change between CUs supporting no PDCP anchor change; information of the PDCP anchor, the information of the PDCP anchor comprising at least one of: identification information of the first candidate device, a public land mobile network (PLMN) identifier, or identification information of an Xn interface of the terminal at the PDCP anchor. corresponding to the PDCP anchor, and a CU of a candidate cell associated with the PDCP anchor; an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; DRB information; SRB information.

34. The method of claim 33, further comprising: the second candidate device sending a second response to the source device, the second response comprising at least one of: RRC configuration information generated by the first DU; an F1 interface identifier of the first DU for the terminal; DRB information of the first DU.

35. The method of any one of claims 31 to 34, comprising: the second candidate device receiving a configuration update request sent by the source device, the configuration update request comprising at least one of the second information; established DRB information; third indication information for indicating that the configuration update request involves keyless configuration update between CUs, or the third indication information for indicating being transparent to the first DU; identifier information of the first DU; identifier information of a candidate cell.

36. The method of any one of claims 31 to 35, wherein, the second candidate device receiving uplink address information of the terminal at the PDCP anchor, comprising: the second candidate device receiving a second notification message sent by the source device, the second notification message comprising uplink address information of the terminal at the PDCP anchor, and further comprising at least one of: an F1 interface identifier of a CU corresponding to the PDCP anchor for the terminal; DRB information of the PDCP anchor; fourth indication information for indicating that the second notification message involves keyless PDCP anchor information notification of service cell change between CUs, or the fourth indication information for indicating being transparent to the first DU.

37. The method of claim 31, wherein, the second candidate device receiving uplink address information of the terminal at the PDCP anchor, comprising: the second candidate device receiving a third message sent by the first candidate device, the third message being used for requesting to establish a user plane data transmission channel with the first DU, and the third message comprising uplink address information of the terminal at the PDCP anchor.

38. The method of claim 37, wherein, the third message further comprising at least one of: an Xn interface identifier of the first candidate device for the terminal; an F1 interface identifier of a CU of the first candidate device for the terminal; sixth indication information for indicating that the first candidate device is a device corresponding to the PDCP anchor; established DRB information; identifier information of the first DU. identifier information of a candidate cell associated with the PDCP anchor.

39. The method of claim 37 or 38, further comprising: sending, by the second candidate device, a fourth message to the first candidate device, the fourth message comprising at least one of: an Xn interface identifier of the second candidate device; an F1 interface identifier of the first DU; DRB information of the first DU; downlink address information of the first DU; RRC configuration information of the first DU.

40. The method of any of claims 31-39, further comprising: sending, by the second candidate device, capability information to the source device, the capability information indicating at least one of: support of keyless update for inter-CU serving cell change; support of one DU connecting multiple CUs.

41. An apparatus for information transmission, comprising: a sending module configured to send first information to a first candidate device corresponding to a packet data convergence protocol anchor (PDCP anchor), the first information comprising at least one of: downlink address information of a terminal at a first distributed unit (DU) associated with the PDCP anchor; related information of a second candidate device associated with the PDCP anchor, the related information comprising at least one of: a cell identifier of a candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; a public land mobile network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

42. The device of claim 41, wherein, The sending module is further configured to send second information to the second candidate device, the second information comprising: uplink address information of the terminal at the PDCP anchor.

43. An apparatus for information transmission, comprising: a receiving module configured to receive first information sent by a source device, the apparatus corresponding to a device corresponding to a packet data convergence protocol anchor (PDCP anchor), the first information comprising at least one of: downlink address information of a terminal at a first distributed unit (DU) associated with the PDCP anchor; related information of a second candidate device associated with the PDCP anchor, the related information comprising at least one of: a cell identifier of a candidate cell of the second candidate device; Xn identifier information of the second candidate device; identifier information of the first DU; a public land mobile network (PLMN) of the candidate cell of the second candidate device; wherein the first DU corresponds to the second candidate device, and the second candidate device is different from the first candidate device.

44. The device of claim 43, wherein, The receiving module is further configured to receive a first request sent by the source device, the first request comprising at least one of: first indication information, the first indication information being used for indicating that a service cell change preparation procedure is preparation for a centralized unit (CU)-inter service cell change, the CU-inter service cell change supporting no key update or the CU-inter service cell change supporting no PDCP anchor change; second indication information, the second indication information being used for indicating that the first candidate device is a device corresponding to a PDCP anchor; association information, the association information being used for indicating at least one of the following: an association relationship between the first candidate device or the PDCP anchor or a CU corresponding to the PDCP anchor and the second candidate device, an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and a CU of a candidate cell associated with the PDCP anchor, or an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; protocol data unit (PDU) session information; data radio bearer (DRB) information; signaling radio bearer (SRB) information.

45. An information transmission apparatus, comprising: a receiving module configured to receive uplink address information of a terminal at a packet data convergence protocol (PDCP) anchor; wherein a second candidate device corresponding to the apparatus is different from a first candidate device corresponding to the PDCP anchor, and a first distributed unit (DU) corresponding to the second candidate device is a DU associated with the PDCP anchor.

46. The device of claim 45, wherein, The receiving module is further configured to receive a second request sent by a source device, the second request comprising at least one of the following: first indication information, the first indication information being used for indicating that a service cell change preparation procedure is preparation for a centralized unit (CU)-inter service cell change, the CU-inter service cell change supporting no key update or the CU-inter service cell change supporting no PDCP anchor change; information of the PDCP anchor, the information of the PDCP anchor comprising at least one of the following: identification information of the first candidate device, a public land mobile network (PLMN) identifier, or identification information of an Xn interface of the terminal at the PDCP anchor; association information, the association information being used for indicating at least one of the following: an association relationship between the first candidate device or the PDCP anchor or a CU corresponding to the PDCP anchor and the second candidate device, an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and a CU of a candidate cell associated with the PDCP anchor, or an association relationship between the first candidate device or the PDCP anchor or the CU corresponding to the PDCP anchor and the first DU; DRB information; SRB information. 47.A network side device, comprising a processor and a memory, the memory storing programs or instructions executable on the processor, the programs or instructions, when executed by the processor, implementing the steps of the information transmission method according to any one of claims 1 to 17, or the programs or instructions, when executed by the processor, implementing the steps of the information transmission method according to any one of claims 18 to 30, or the programs or instructions, when executed by the processor, implementing the steps of the information transmission method according to any one of claims 31 to 40. 48.A readable storage medium, the readable storage medium storing programs or instructions, the programs or instructions, when executed by a processor, implementing the steps of the information transmission method according to any one of claims 1 to 17, or the steps of the information transmission method according to any one of claims 18 to 30, or the steps of the information transmission method according to any one of claims 31 to 40. 49.A computer program product, the computer program product being stored in a storage medium, the computer program product being executed by at least one processor to implement the steps of the information transmission method according to any one of claims 1 to 17, or the steps of the information transmission method according to any one of claims 18 to 30, or the steps of the information transmission method according to any one of claims 31 to 40.

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