Communication method and communication device

Abstract

A communication method and a communication device can be applied to an IAB system and can also be applied to an access network system comprising a CU-DU separation architecture, and in a scene in which terminal equipment accessing a relay node is switched from a source cell to a target cell, random access-free switching configuration information is sent to the terminal equipment, so that the terminal equipment is switched from the source cell to the target cell. The terminal equipment does not need to execute a random access process to access the target cell, so that the switching interruption time of switching from the source cell to the target cell can be reduced, and the communication performance of the terminal equipment can be improved. The method may comprise: determining first beam information to be used by a terminal device for communication with a target cell, the first beam information comprising a beam identifier of a first beam; the communication of the terminal equipment is switched from a source cell to a target cell, and the source cell and the target cell of the terminal equipment are cells of the relay node; and sending random access-free switching configuration information to the terminal equipment, wherein the random access-free switching configuration information comprises the first beam information.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a communication method and a communication device. Background Art

[0002] Integrated access and backhaul (IAB) can not only meet the needs of densely deployed base stations, but also meet the needs of flexible deployment of optical fibers and save the cost of optical fiber deployment. IAB is a relay solution that may include an IAB node and an IAB donor, where the IAB donor is the host node of the IAB node. Among them, the IAB node may also be called a relay node or a relay device, etc. The child node of the IAB node may be another IABnode or a user equipment (UE), and the parent node of the IAB node may be another IAB node or another IABdonor. The IAB node consists of a mobile termination (MT) part and a distributed unit (DU) part, which may be represented as IAB-MT and IAB-DU, respectively. When the IAB node faces its parent node, it is an IAB-MT; when the IAB node faces its child node, it is an IAB-DU. The IAB donor may also be called a host device, a host node, or a donor base station, etc. IAB donor consists of a centralized unit (CU) part and a DU part, which can be represented as IAB-donor-CU and IAB-donor-DU respectively.

[0003] Since the IABnode is mobile, the communication of the connected UE accessing the IABnode may be switched from one cell to another, that is, from a source cell to a target cell. How to reduce the handover interruption time is a technical problem to be solved urgently. Summary of the invention

[0004] The embodiments of the present application provide a communication method and a communication device, which can reduce the switching interruption time of a terminal device from a source cell to a target cell, thereby helping to improve the communication performance of the terminal device.

[0005] In a first aspect, an embodiment of the present application provides a communication method, which may be executed by a first host node, or by a device in the first host node, such as a chip, a chip system, or a processor. Optionally, the method may be executed by a CU of the first host node, or by a chip or a processor in the CU. The method may include: determining first beam information to be used by a terminal device to communicate with a target cell, the first beam information including a beam identifier of the first beam; the communication of the terminal device will be switched from a source cell to a target cell, the source cell and the target cell of the terminal device being cells of relay nodes; and sending random access-free switching configuration information to the terminal device, the random access-free switching configuration information including the first beam information.

[0006] Through this method, the terminal device can communicate directly with the target cell based on the first beam information without performing a random access process (including beam selection) to access the target cell. This can reduce the switching interruption time from the source cell to the target cell, and help improve the communication performance of the terminal device.

[0007] In one possible implementation, before determining the first beam information, the CU of the first host node receives beam measurement information of the target cell from the source DU, and the beam measurement information includes a beam identifier of at least one beam (one beam identifier is used to identify one beam), and the at least one beam includes the first beam. Thus, the CU of the first host node can determine the first beam based on the beam measurement information; or the CU of the first host node can send the beam measurement information to the target DU so that the target DU determines the first beam. Among them, the source DU and the target DU both belong to the relay node, that is, the relay node includes the source DU and the target DU.

[0008] The CU of the first host node may directly receive the beam measurement information of the target cell from the source DU, that is, the source DU directly sends the beam measurement information of the target cell to the CU of the first host node. The beam measurement information may be included in a radio resource control (RRC) message, which may be included in the F1AP signaling.

[0009] The CU of the first host node may also receive the beam measurement information of the target cell from the source DU through the second host node, that is, the source DU sends the beam measurement information of the target cell to the CU of the second host node, and the CU of the second host node then sends the beam measurement information of the target cell to the CU of the first host node. The beam measurement information sent by the source DU to the CU of the second host node may be included in an RRC message, which may be included in F1AP signaling; the beam measurement information sent by the CU of the second host node to the CU of the first host node is included in XnAP signaling.

[0010] Among them, the relay node has established a connection with the first host node, which can be understood as the source DU of the relay node has established an F1 connection with the CU of the first host node. Alternatively, the connection between the relay node and the host node is migrated from the second host node to the first host node, which can be understood as the source DU of the relay node first establishes an F1 connection with the CU of the second host node, and as the relay node moves, the F1 connection is disconnected, and the target DU of the relay node establishes an F1 connection with the CU of the first host node.

[0011] Optionally, the beam measurement information also includes the signal quality of at least one beam, specifically the signal quality of each beam in the at least one beam, so that the first beam can be determined based on the signal quality of the at least one beam. The first beam can be the beam with the best signal quality in the at least one beam.

[0012] In a possible implementation manner, the CU of the first host node may determine the first beam information in any of the following ways:

[0013] Mode 1: The CU of the first donor node directly determines the first beam from at least one beam based on the beam measurement information of the target cell, and then determines the first beam information;

[0014] Mode 2: The CU of the first host node sends the beam measurement information of the target cell to the target DU, and the target DU determines the first beam information based on the beam measurement information of the target cell, and the target DU sends the first beam information to the CU of the first host node; optionally, the first beam information is directly included in the F1AP signaling, or the first beam information is included in the RRC message, and the RRC message is included in the F1AP signaling;

[0015] Mode 3: The CU of the first host node receives the first beam information from the CU of the second host node, that is, the first beam information is determined by the CU of the second host node; the first beam information is included in the XnAP signaling.

[0016] In a possible implementation, for the above-mentioned method 1 or method 3, the CU of the first host node may also send the first beam information to the target DU (sent to the target DU through F1AP signaling), and the target DU sends the first beam information to the CU of the first host node (sent to the CU of the first host node through an RRC message, and the RRC message is included in the F1AP signaling). The target DU sends the first beam information to the CU of the first host node, which is used for the CU of the first host node to generate a switching command, and the switching command may include random access-free switching configuration information.

[0017] In a possible implementation, when the CU of the first host node sends the random access-free switching configuration information to the terminal device, it may include: sending the random access-free switching configuration information to the terminal device through the source DU, which can be understood as the CU of the first host node sending the random access-free switching configuration information to the source DU, and the source DU then transparently transmits the random access-free switching configuration information to the terminal device; or, sending the random access-free switching configuration information to the terminal device through the second host node and the source DU, that is, the CU of the first host node sends the random access-free switching configuration information to the CU of the second host node through the Xn interface, and the CU of the second host node sends the random access-free switching configuration information to the source DU, and the source DU then transparently transmits the random access-free switching configuration information to the terminal device.

[0018] In a possible implementation, the CU of the first host node receives the first information before determining the first beam information, and determines based on the first information that the terminal device needs to perform a random access-free switching process. Only when it is determined that the terminal device needs to perform a random access-free switching process, the CU of the first host node will send the random access-free switching configuration information to the terminal device.

[0019] In a possible implementation, the first information comes from the second host node, and the first information indicates that the terminal device needs to perform a random access-free handover process. That is, the second host node determines that the terminal device needs to perform a random access-free handover process and indicates it to the first host node.

[0020] In a possible implementation, the first information comes from the source DU or the second host node, and the first information is used to indicate that the source cell of the terminal device and the target cell of the terminal device are cells of the relay node. That is, the source DU or the second host node can send the first information directly or indirectly indicating that the source cell and the target cell are cells of the relay node to the first host node, and the first host node determines that the terminal device needs to perform a random access-free switching process based on this.

[0021] In one possible implementation, the above-mentioned first information comes from the target DU, and the first information indicates the cell information of the first cell, and the first cell is the cell activated when the relay node connects to the second host node. That is to say, the first cell is the cell activated by the source DU when the source DU establishes an F1 connection with the CU of the second host node. Thus, the CU of the first host node determines that the terminal device needs to perform a random access-free switching process based on the first information, which may include: receiving the cell identifier of the source cell and the cell identifier of the target cell from the second host node; in response to the cell identifier of the source cell being in the cell information of the first cell and the cell identifier of the target cell being in the cell information of the second cell, determining that the source cell and the target cell are cells of the relay node; in response to the source cell and the target cell being cells of the relay node, determining that the terminal device needs to perform a random access-free switching process.

[0022] In the second aspect, an embodiment of the present application provides a communication method, which can be executed by a second host node, or by a device in the second host node, such as a chip, a chip system or a processor. Optionally, the method can be executed by the CU of the second host node, or by a chip or a processor in the CU. The method may include: determining the first beam information to be used by the terminal device to communicate with the target cell, the first beam information including the beam identifier of the first beam; the communication of the terminal device will be switched from the source cell to the target cell, and the source cell and the target cell of the terminal device are cells of relay nodes; sending random access-free switching configuration information to the terminal device, and the random access-free switching configuration information includes the first beam information. Thus, the terminal device can communicate directly with the target cell based on the first beam information, without performing a random access process (including beam selection) to access the target cell, which can reduce the switching interruption time from the source cell to the target cell, and help improve the communication performance of the terminal device.

[0023] Among them, the relay node has established a connection with the first host node, which can be understood as the source DU of the relay node has established an F1 connection with the CU of the first host node. Alternatively, the connection between the relay node and the host node is migrated from the second host node to the first host node, which can be understood as the source DU of the relay node first establishes an F1 connection with the CU of the second host node, and as the relay node moves, the F1 connection is disconnected, and the target DU of the relay node establishes an F1 connection with the CU of the first host node.

[0024] In a possible implementation, before determining the first beam information, the CU of the second host node receives beam measurement information of a target cell from the source DU, where the beam measurement information includes a beam identifier of at least one beam, and the at least one beam includes the first beam. Thus, the CU of the second host node can determine the first beam based on the beam measurement information.

[0025] Optionally, the beam measurement information also includes the signal quality of at least one beam, specifically the signal quality of each beam in the at least one beam, so that the first beam can be determined based on the signal quality of the at least one beam. The first beam can be the beam with the best signal quality in the at least one beam.

[0026] In one possible implementation, the CU of the second host node sends the beam measurement information of the target cell received from the source DU to the CU of the first host node, so that the CU of the first host node can determine the first beam information based on this.

[0027] In a possible implementation, the CU of the second host node directly determines the first beam from at least one beam based on the beam measurement information of the target cell, and further determines the first beam information.

[0028] In one possible implementation, after determining the first beam information, the CU of the second host node sends the first beam information to the CU of the first host node, so that the CU of the first host node generates random access-free switching configuration information and sends it to the CU of the second host node. The CU of the second host node sends the random access-free switching configuration information to the terminal device through the source DU.

[0029] In one possible implementation, the method provided by the second aspect also includes: sending first information to the first host node; the first information is used to indicate that the source cell and the target cell of the terminal device are cells of the relay node (the first information can be determined by the CU of the second host node or comes from the source DU), or the first information indicates that the terminal device needs to perform a random access-free switching process.

[0030] In a possible implementation, the method provided in the second aspect further includes: sending a cell identifier of the source cell and a cell identifier of the target cell to the first host node so that the first host node determines whether the source cell and the target cell are cells of the relay node.

[0031] In a third aspect, an embodiment of the present application provides a communication method, which may be executed by a target DU, or by a device in the target DU, such as a chip, a chip system or a processor. The target DU belongs to a relay node, and the source cell and the target cell of the terminal device are cells of the relay node. The method may include: receiving beam measurement information of a target cell of a terminal device from a first host node, the beam measurement information including a beam identifier of at least one beam; based on the beam measurement information of the target cell, determining first beam information to be used by the terminal device to communicate with the target cell, the first beam information including a beam identifier of a first beam, and at least one beam including a first beam; sending the first beam information to the first host node.

[0032] It can be seen that the target DU can determine the first beam information based on the beam measurement information of the target cell from the first host node, and send it to the first host node, so that the first host node can send the first beam information to the terminal device, so that the terminal device can access the target cell without performing a random access process, thereby reducing the switching interruption time of the terminal device from the source cell to the target cell, which helps to improve the communication performance of the terminal device.

[0033] In a possible implementation, the method provided by the third aspect also includes: sending first information to the first host node, the first information indicating cell information of the first cell, the first cell being the cell activated when the relay node is connected to the second host node. That is, the first cell can be the cell activated when the source DU of the relay node establishes an F1 connection with the CU of the second host node. The target DU sends the cell information of the first cell to the first host node, so that the first host node determines whether the source cell and the target cell of the terminal device are cells of the relay node based on the cell information of the first cell. Optionally, the target DU can obtain the cell information of the first cell from the source DU.

[0034] In a fourth aspect, an embodiment of the present application provides a communication method, which can be executed by a target DU, or by a device in the target DU, such as a chip, a chip system or a processor. The target DU belongs to a relay node, and the source cell and the target cell of the terminal device are cells of the relay node. The method may include: receiving first beam information from a first host node, the first beam information including a beam identifier of a first beam, and the first beam information is beam information to be used by the terminal device to communicate with the target cell; sending the first beam information to the first host node, the first beam information being included in an RRC message. The RRC message is included in F1AP signaling.

[0035] It can be seen that the first host node sends the first beam information to the target DU, so that the target DU encapsulates it in an RRC message, and sends the RRC message to the first host node, so that the first host node can send the first beam information to the terminal device, so that the terminal device can access the target cell without performing a random access process, thereby reducing the switching interruption time of the terminal device from the source cell to the target cell, which helps to improve the communication performance of the terminal device.

[0036] In a possible implementation, the method provided in the third aspect also includes: sending first information to the first host node, the first information indicating cell information of the first cell, the first cell being a cell activated when the relay node connects to the second host node. The target DU sends the cell information of the first cell to the first host node, so that the first host node determines whether the source cell and the target cell of the terminal device are cells of the relay node based on the cell information of the first cell. Optionally, the target DU can obtain the cell information of the first cell from the source DU.

[0037] In a fifth aspect, an embodiment of the present application provides a communication method, which can be executed by a source DU, or by a device in the source DU, such as a chip, a chip system or a processor. The source DU belongs to a relay node, and the source cell and the target cell of the terminal device are cells of the relay node. The method may include: receiving random access-free switching configuration information from a first host node, the random access-free switching configuration information includes first beam information, and the first beam information includes a first beam; sending random access-free switching configuration information to the terminal device, the first beam information is the beam information to be used by the terminal device to communicate with the target cell; the communication of the terminal device will be switched from the source cell to the target cell, and the source cell and the target cell are cells of the relay node.

[0038] It can be seen that the first host node sends the first beam information to the terminal device through the source DU, so that the terminal device can access the target cell without performing a random access process, thereby reducing the switching interruption time of the terminal device from the source cell to the target cell, which helps to improve the communication performance of the terminal device.

[0039] In a possible implementation, the random access-free switching configuration information from the first host node is received by the second host node. That is, the first host node sends the first beam information to the source DU through the second host node, so that the source DU transparently transmits the first beam information to the terminal device.

[0040] Among them, the relay node has established a connection with the first host node, which can be understood as the source DU of the relay node has established an F1 connection with the CU of the first host node. Alternatively, the connection between the relay node and the host node is migrated from the second host node to the first host node, which can be understood as the source DU of the relay node first establishes an F1 connection with the CU of the second host node, and as the relay node moves, the F1 connection is disconnected, and the target DU of the relay node establishes an F1 connection with the CU of the first host node.

[0041] In a possible implementation, the method provided in the fifth aspect further includes: sending beam measurement information of the target cell to the first host node; or, sending the beam measurement information of the target cell to the first host node through the second host node. Thus, the first host node can obtain the beam measurement information of the target cell, and then determine the first beam information based on the beam measurement information. The beam measurement information includes a beam identifier of at least one beam, and the at least one beam includes the first beam.

[0042] In a possible implementation, the method provided in the fifth aspect also includes: sending first information, the first information being used to indicate that the source cell of the terminal device and the target cell of the terminal device are cells of the relay node. Optionally, the source DU sends the first information directly to the first host node; or, the source DU sends the first information to the first host node through the second host node, so that the first host node can determine, based on the first information, that the terminal device needs to perform a random access-free switching process. Optionally, the source DU sends the first information to the second host node, and the second host node determines, based on the first information, that the terminal device needs to perform a random access-free switching process, so that the second host node can indicate to the first host node that the terminal device needs to perform a random access-free switching process.

[0043] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a first host node, or a device in the first host node, or a device that can be used in combination with the first host node. The communication device may also be a chip system. The communication device may execute the method described in the first aspect. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the method and beneficial effects described in the first aspect above.

[0044] In the seventh aspect, an embodiment of the present application provides a communication device, which may be a second host node, or a device in the second host node, or a device that can be used in combination with the second host node. Among them, the communication device may also be a chip system. The communication device may execute the method described in the second aspect. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the method and beneficial effects described in the second aspect above.

[0045] In an eighth aspect, an embodiment of the present application provides a communication device, which may be a target DU, or a device in a target DU, or a device that can be used in combination with a target DU. The communication device may also be a chip system. The communication device may execute the method described in the third aspect or the fourth aspect above. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the methods and beneficial effects described in the third aspect or the fourth aspect above.

[0046] In the ninth aspect, an embodiment of the present application provides a communication device, which may be a source DU, a device in the source DU, or a device that can be used in combination with the source DU. Among them, the communication device may also be a chip system. The communication device may execute the method described in the fifth aspect above. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more units or modules corresponding to the above functions. The unit or module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the methods and beneficial effects described in the fifth aspect above.

[0047] In the tenth aspect, an embodiment of the present application provides a communication device, the communication device includes a processor, the processor is coupled to a memory, the memory is used to store programs or instructions, when the program or instructions are executed by the processor, the communication device executes the method described in any one of the first to fifth aspects.

[0048] In the eleventh aspect, an embodiment of the present application provides a communication device, which includes a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method described in any one of the first to fifth aspects through a logic circuit or by executing code instructions.

[0049] In the twelfth aspect, an embodiment of the present application provides a computer-readable storage medium, in which a computer program or instructions are stored. When the computer program or instructions are executed by a communication device, the method described in any one of the first to fifth aspects is implemented.

[0050] In the thirteenth aspect, an embodiment of the present application provides a computer program product comprising instructions, which, when a communication device reads and executes the instructions, enables the communication device to perform any method in any one of the first to fifth aspects.

[0051] In a fourteenth aspect, an embodiment of the present application provides a communication system, the communication system comprising a first host node and a target DU, the first host node being used to execute the method provided in the first aspect, and the target DU being used to execute the method provided in the third aspect or the fourth aspect. Alternatively, the communication system comprises a first host node, a second host node, and a target DU, the first host node being used to execute the method provided in the first aspect, the second host node being used to execute the method provided in the second aspect, and the target DU being used to execute the method provided in the third aspect or the fourth aspect. Optionally, the communication system further comprises a source DU for executing the method provided in the fifth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of a wireless relay scenario;

[0053] Figure 2 This is an example diagram of a distributed unit migration (DU migration) scenario;

[0054] Figure 3 It is a schematic diagram of a non-contention random access process;

[0055] Figure 4 This is an example diagram of a system architecture using an embodiment of the present application;

[0056] Figure 5 It is a flow chart of a communication method provided in an embodiment of the present application;

[0057] Figure 5A It is a flowchart of determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application;

[0058] Figure 6 It is a flowchart of another communication method provided in an embodiment of the present application;

[0059] Fig. 6A It is another flowchart of determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application;

[0060] Figure 6B It is another flowchart of determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application;

[0061] Figure 7 is a structural diagram of a communication device provided in an embodiment of the present application;

[0062] Figure 8 It is a structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] In the present application, words such as "first" and "second" are used to distinguish between identical or similar items with substantially the same functions and effects. Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit them to be different. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previously associated objects are in an "or" relationship.

[0064] It should be understood that in this application, "at least one" means one or more; "plurality" means two or more. In addition, "equal to" in this application can be used in conjunction with "greater than" or "less than". When "equal to" is used in conjunction with "greater than", the technical solution of "greater than" is adopted; when "equal to" is used in conjunction with "less than", the technical solution of "less than" is adopted.

[0065] The following is an explanation of the relevant names or terms involved in this application to facilitate understanding by those skilled in the art.

[0066] 1. IAB Network

[0067] In an IAB network, an IAB node may also be called a relay node (RN) or a relay device, etc. An IAB node can provide wireless access services for UEs, and the service data of UEs is transmitted by the IAB node to the IAB donor via a backhaul link.

[0068] IAB node consists of IAB-MT and IAB-DU. When IAB node faces its parent node, it can act as IAB-MT; when IAB node faces its child node (child node may be another IABnode or UE), it can be regarded as a network device, that is, the role of IAB-DU.

[0069] IAB donor consists of IAB-donor-CU and IAB-donor-DU. IAB donor can be an access network device with complete base station functions, or it can be an access network device with separated CU and DU. IAB donor is connected to the core network element that provides services for UE (for example, connected to the 5G core network (5G core, 5GC) element) and provides wireless backhaul function for IAB node. Among them, IAB-donor CU may be in the form of separated control plane (CP) and user plane (UP). For example, IAB-donor-CU can be composed of one IAB-donor-CU-CP and one (or more) IAB-donor-CU-UP.

[0070] In an IAB network, a transmission path between a UE and an IAB donor may include one or more IAB nodes. Each IAB node not only maintains a backhaul link to the parent node, but also maintains an access link to the child node. If the child node of an IAB node is a UE, the link between the IAB node and the UE is an access link. If the child node of an IAB node is another IAB node, the link between the IAB node and the other IAB nodes is a backhaul link. For example, see Figure 1 In the wireless relay scenario shown, in the path "UE1→IAB node 4→IAB node3→IAB node 1→IAB donor", UE1 accesses IAB node 4 through the access link, IAB node 4 is connected to IAB node3 through the backhaul link, IAB node 3 is connected to IAB node 1 through the backhaul link, and IAB node 1 is connected to the IAB donor through the backhaul link. Figure 1 In the figure, black bidirectional arrows represent backhaul links, and gray bidirectional arrows represent access links.

[0071] The relay node in the embodiment of the present application may be an access IAB node. The access IAB node refers to the IAB node accessed by the UE. For example, see Figure 1 , in the path “UE1→IAB node 4→IAB node 3→IAB node 1→IAB donor”, ​​IAB node 4 is the access IAB node.

[0072] The host node in the embodiment of the present application may be an IAB donor, and the CU and DU of the IAB donor may adopt a separate architecture or not, depending on the specific circumstances.

[0073] The CU may be a device under an open radio access network (O-RAN or ORAN) architecture, such as an open CU. The DU (such as IAB-DU) may also be a device under an O-RAN architecture, such as an open DU or other device.

[0074] 2. Distributed Unit Migration (DUmigration)

[0075] With the development of communication technology and the evolution of standards, IABnode may have mobility, for example, IABnode may be installed on a mobile object, and IABnode may move with the movement of the mobile object. Exemplarily, IABnode may be installed on a vehicle, and move with the movement of the vehicle. IABnode installed on a vehicle may be called a vehicle mounted relay (VMR) node. IABnode with mobility may be called a mobile IABnode (mobile IABnode, mIAB node).

[0076] For the mAB node, due to the limited coverage area of ​​the IAB-donor-CU, it is impossible to always maintain the F1 connection with the IAB-DU. Therefore, considering the mobility of the IAB node or the load balancing requirements on the radio access network (RAN) side, the F1 connection of the IAB-DU can be migrated from the donor-CU terminated by the source F1 to the donor-CU terminated by the target F1.

[0077] For example, see Figure 2 An example diagram of a distributed unit migration scenario is shown. Figure 2In the figure, IABnode2 includes two logical DUs, that is, IAB-DU 2 includes IAB-DU 2a and IAB-DU 2b. Before the movement, IABnode 2 has established an F1 connection with IAB-donor-CU 1 through IAB-DU 2a, IAB-MT 2 has established an RRC connection with IAB-donor-CU 2, and IAB-DU2b is in a pending activation state, that is, before IABnode2 moves, the F1 connection of IABnode 2 is terminated at IAB-donor-CU 1. After IABnode 2 moves, IAB-donor-CU 1 or the OAM device may decide to migrate the F1 connection of IABnode 2 to IAB-donor-CU 3, thereby triggering IAB node 2 to perform the distributed unit migration process, that is, activating IAB-DU 2b and establishing an F1 connection with IAB-donor-CU 3 through IAB-DU 2b. At this time, IAB-MT 2 can still maintain the RRC connection with IAB-donor-CU 2.

[0078] It should be noted that Figure 2 Taking IAB-donor-CU 1, IAB-donor-CU 2 and IAB-donor-CU 3 as three different CUs as an example, in actual applications, it may happen that IAB-donor-CU 1 and IAB-donor-CU 2 are the same CU (that is, the donor-CU terminated by source F1 and the donor-CU terminated by non-F1 are the same CU), or IAB-donor-CU 2 and IAB-donor-CU 3 are the same CU (that is, the donor-CU terminated by non-F1 and the donor-CU terminated by target F1 are the same CU).

[0079] It should be noted that, for mABnode, when it does not need to perform distributed unit migration (for example, the cell identity of mABnode conflicts with the cell identity of the neighboring cell due to mobility), mABnode may also include two activated logical DUs (for example Figure 2 IAB-DU 2a and IAB-DU 2b in the .

[0080] 3. Random access (RA / RACH) process in 5G system

[0081] The random access process in the 5G system refers to the UE sending a preamble to a network device (such as a gNB) to access the network device. The random access process can be divided into a competitive random access process and a non-competitive random access process. For example, see Figure 3 The non-contention random access process shown may include:

[0082] Step 0, random access preamble allocation. The gNB allocates random access resources, such as a random access preamble, to the UE. The message sent by the gNB to the UE may include a preamble indication.

[0083] Step 1, the UE sends a random access request, i.e., msg1, to the gNB. The random access request may include a random access preamble. Before sending a random access request to the gNB, the UE measures multiple downlink beams. Exemplarily, taking the association relationship between the downlink beam and the synchronization signal and physical broadcast channel block (SSB) as an example, the UE measures the SSBs of the four beams SSB#1, SSB#2, SSB#3, and SSB#4. Assuming that the signal quality of SSB#3 is better, the UE selects the time-frequency resource corresponding to SSB#3 to send a random access request. After the gNB receives the random access preamble on the time-frequency resource, it knows that when communicating with the UE, the beam corresponding to SSB#3 should be used.

[0084] Step 2: The gNB feeds back a random access response, i.e., msg2, to the UE. The gNB may send a random access response to the UE via the beam determined in step 1, such as SSB#3.

[0085] Through the random access process, the gNB can determine the timing advance (TA) information of the UE through the received random access preamble and carry the TA in the random access response. Then, after receiving the random access response, the UE can use the carried TA to adjust the uplink transmission time to complete uplink synchronization with the gNB. In other words, through the random access process, the UE completes the uplink synchronization with the gNB. In addition, the UE can also complete the beam alignment with the gNB to improve the communication quality.

[0086] 4. Random access channel-less handover (RACH-less HO)

[0087] When a UE switches from a source cell to a target cell, it needs to complete uplink synchronization with the target cell, that is, obtain the TA of the target cell. In a general cell switching process, the UE completes uplink synchronization with the target cell through a random access process, which will cause a period of switching interruption time.

[0088] In Long Term Evolution (LTE), RACH-lessHO is introduced. The source cell indicates the TA of the target cell in the handover command sent to the UE, and the UE directly uses the TA to send an uplink message to the target cell. In other words, when the UE obtains the TA, it completes the uplink synchronization with the target cell, avoiding or reducing the uplink synchronization with the target cell through the RACH process, which can reduce the handover interruption time.

[0089] The following is an introduction to the application scenarios and system architecture of this application.

[0090] For mIABnode, during the mobile process, the communication of the connected UE accessing mIABnode may be switched from one cell to another, that is, from the source cell to the target cell. If the UE completes the uplink synchronization with the target cell through the RACH process, it will bring a period of handover interruption time. Therefore, how to reduce the handover interruption time is a technical problem that needs to be solved urgently.

[0091] In view of this, an embodiment of the present application provides a communication method and a communication device, which can reduce the switching interruption time of a terminal device from a source cell to a target cell, thereby helping to improve the communication performance of the terminal device.

[0092] In one implementation, the embodiment of the present application can be applied to the Intra-CU scenario, that is, the F1 connection between the mIAB node and the IAB-donor-CU is not migrated during the movement. In the Intra-CU scenario, the cell identifier of the cell of the moved mIABnode may conflict with the cell identifiers of other surrounding cells. The conflict may cause the UE to switch from the source cell to the target cell. At this time, the communication method provided in the embodiment of the present application can be used to reduce the interruption time.

[0093] In another implementation, the embodiment of the present application may be applied to an Inter-CU scenario, that is, during the movement of the mIAB node, the F1 connection between the mIAB node and the IAB-donor-CU is migrated, for example, from IAB-donor-CU 1 to IAB-donor-CU 3. The Inter-CU scenario may include but is not limited to a distributed unit migration scenario. For example, the distributed unit migration scenario may refer to Figure 2 The scenario example diagram shown. In the distributed unit migration scenario, the F1 connection between mIABnode and IAB-donor-CU migrates from IAB-donor-CU 1 to IAB-donor-CU 3, and the UE accessing mIABnode may switch from the cell of IAB-DU 2a to the cell of IAB-DU 2b. At this time, the communication method provided in the embodiment of the present application can be used to reduce the interruption time.

[0094] The embodiments of the present application are not only applicable to the IAB system, but also to the access network system including the CU-DU separation architecture. For example, IAB-DU 2a can be gNB 2-DUa, and IAB-DU 2b can be gNB 2-DUb, that is, gNB 2-DUa and gNB 2-DUb are two DUs of gNB 2.

[0095] See also Figure 4 , is an example diagram of a system architecture applying an embodiment of the present application. Figure 4 The system architecture shown includes a relay node 401 , a terminal device 402 , and a first host node 403 .

[0096] Among them, the relay node 401 may include a source DU 4011 and a target DU 4012. The source DU 4011 and the target DU 4012 may be two logical DUs of the same IABnode, or two DUs of the same gNB. The source DU 4011 includes a source cell of the terminal device 402, and the target DU 4012 includes a target cell of the terminal device 402. In an embodiment of the present application, the target DU may determine the first beam information to be used by the terminal device to communicate with the target cell.

[0097] The terminal device 402 may be a mobile device such as a UE, or a device acting as a terminal device, such as an IAB-MT, etc. The mobile device may be, for example, a mobile phone, a tablet computer, a laptop computer, a PDA, a mobile internet device (MID), a wearable device (such as a smart watch, a smart bracelet, a pedometer, etc.), a vehicle-mounted device (such as a car, a bicycle, an electric vehicle, an airplane, a ship, a train, a high-speed train, etc.), a satellite terminal, a virtual reality (VR) device, an augmented reality (AR) device, a smart point of sale (POS) machine, a customer-premises equipment (CPE), a wireless terminal in industrial control, a smart home device (such as a refrigerator, a TV, an air conditioner, an electric meter, etc.), an intelligent robot, a robotic arm, a workshop device, a wireless terminal in unmanned driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, or a wireless terminal in a smart home, a flying device (such as an intelligent robot, a hot air balloon, a drone, an airplane), etc. For the convenience of description, the terminal device in the embodiment of the present application takes UE as an example.

[0098] The first host node 403 is a host node that has established an F1 connection with the relay node 401. In the embodiment of the present application, the first host node 403 can determine the first beam information to be used by the terminal device to communicate with the target cell, and send the first beam information to the terminal device through the source DU.

[0099] Optional, Figure 4 The system architecture shown also includes a second host node 404. The second host node 404 is the host node to which the relay node 401 is connected before the F1 connection migration. That is, the relay node 401 establishes an F1 connection with the second host node 404 before establishing an F1 connection with the first host node 403. In this case, the source DU 4011 establishes an F1 connection with the CU of the second host node 404, and due to the movement of the relay node 401, the target DU 4012 is activated and establishes an F1 connection with the CU of the first host node 403. In an embodiment of the present application, the second host node 404 may also determine the first beam information to be used by the terminal device to communicate with the target cell, and send it to the first host node 403, so that the first host node 403 sends the first beam information to the terminal device through the source DU.

[0100] Figure 4 The system architecture shown may also be an O-RAN, a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system. Figure 4 The system architecture shown may also be a communication system that integrates two or more of the above systems.

[0101] Combine the following Figure 4 The system architecture shown in the figure is used to describe the communication method provided by the embodiment of the present application in detail. For the convenience of description, the CU of the first host node is CU3, the CU of the second host node is CU1, the relay node is mIABnode (including the source DU and the target DU) is used as an example, and the terminal device is UE as an example.

[0102] See also Figure 5 , is a flow chart of a communication method provided in an embodiment of the present application, and the method may include mode 1 and mode 2, either of which can be selected. It can be understood that in mode 1 shown in steps 501-1 to 505-1, the target DU determines the first beam information, and CU3 sends the first beam information to the UE through random access-free switching configuration information. In mode 2 shown in steps 501-2 to 505-2, CU3 determines the first beam information, and CU3 sends the first beam information to the UE through random access-free switching configuration information.

[0103] Method 1:

[0104] 501-1, CU3 sends the beam measurement information of the target cell of the UE to the target DU. Correspondingly, the target DU receives the beam measurement information of the target cell of the UE from CU3.

[0105] Figure 5 The illustrated embodiment takes the case where the source DU and the target DU have established F1 connections with CU3 respectively, i.e., the Intra-CU scenario. Exemplarily, CU3 sends the beam measurement information of the target cell to the target DU via F1AP signaling, i.e., the F1AP signaling includes the beam measurement information of the target cell. The F1AP signaling may be, for example, a UE context setup request signaling (i.e., UE Context SetupRequest signaling).

[0106] Among them, the beam measurement information of the target cell includes the beam identifier of at least one beam of the target cell. At least one beam may include a downlink beam and / or an uplink beam. The beam identifier is used to identify the beam. Optionally, a reference signal index may be used to identify the beam. The reference signal index may be, for example, an SSB index (index), a channel state information reference signal (CSI-RS) or other reference signal index (index); optionally, an identifier of the reference signal may be used to identify the beam, such as a transmission configuration indicator (TCI) state (state) identifier (identifier, ID), etc. One beam corresponds to one beam identifier. In the embodiment of the present application, the beam identifier takes the SSB index as an example.

[0107] Optionally, the beam measurement information of the target cell may also include the signal quality of at least one beam of the target cell, such as the signal quality of the SSB identified by each SSB index. The signal quality may be one or more of the following: reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), signal to interference plus noise ratio (SINR), received signal strength indicator (RSSI), etc.

[0108] The target cell is determined by CU3 based on the neighboring cell measurement report sent by the source DU. The neighboring cell refers to the neighboring cell of the source cell of the UE, that is, the neighboring cell of the serving cell before the cell switching. The neighboring cell measurement report includes the cell identifier of at least one neighboring cell and the beam measurement information of at least one neighboring cell. The process of CU3 determining the target cell will be in Figure 5A This is described in detail in step 500-d shown.

[0109] 502-1, the target DU determines first beam information based on the beam measurement information of the target cell. The first beam information is the beam information to be used by the UE to communicate with the target cell.

[0110] The target DU determines the first beam information to be used by the UE to communicate with the target cell based on the beam measurement information of the target cell. The first beam information includes the beam identifier of the first beam. For example, the beam measurement information of the target cell includes the signal quality of each SSB from SSB#1 to SSB#4, and the signal quality of SSB#3 is the best, then the beam corresponding to SSB#3 is selected as the first beam, and the beam identifier of the first beam is SSB#3. In other words, after the UE switches from the source cell to the target cell, it can directly use the first beam when communicating with the target cell, for example, using the beam corresponding to SSB#3 to send uplink data to the target cell. The UE does not need to perform measurements again, nor does it need to send a random access preamble to the target cell, which helps to reduce the switching interruption time.

[0111] 503-1, the target DU sends the first beam information to CU3.

[0112] After determining the first beam information, the target DU sends the first beam information to CU3 so that CU3 generates a switching command.

[0113] In one implementation, the target DU includes the first beam information in an RRC message, and sends the RRC message to CU3 through F1AP signaling, for example, sending the RRC message to CU3 through UE context setup response signaling (i.e., UE Context Setup Response signaling). The first beam information is included in the RRC message, for example, the first beam information is included in an RRC container (RRC-Container). Including the first beam information in the RRC container can be understood as RRC layer-related encoding of the first beam information. This implementation can be understood as F1AP signaling implicitly including the first beam information. It is a possible way for F1AP signaling to implicitly indicate the first beam information through an RRC message, and F1AP signaling may implicitly indicate the first beam information through other messages.

[0114] In another implementation, the target DU directly sends the first beam information to CU3 through F1AP signaling, that is, the F1AP signaling explicitly includes the first beam information. For example, the target DU directly sends the first beam information to CU3 through UE Context SetupResponse signaling.

[0115] 504-1, CU3 sends random access-free switching configuration information to the source DU. Correspondingly, the source DU receives the random access-free switching configuration information from CU3. The random access-free switching configuration information includes the first beam information.

[0116] CU3 generates a handover command based on the first beam information from the target DU, and the handover command may include random access-free handover configuration information, and the random access-free handover configuration information includes the first beam information. That is, CU3 generates a handover command instructing the UE not to perform a random access handover to distinguish it from a handover command for a non-random access-free handover, and the handover command for a non-random access-free handover instructs the UE to perform a random access procedure to access the target cell.

[0117] Optionally, the random access-free switching configuration information may further include TA indication information, where the TA indication information is used to instruct the UE to use the TA of the source cell to perform uplink synchronization with the target cell.

[0118] Optionally, the random access-free switching configuration information may further include uplink grant (UL Grant) indication information, where the UL Grant indication information is used to indicate resources, such as time-frequency resources, used by the UE for the first uplink data transmission.

[0119] In one implementation, CU3 includes the random access-free switching configuration information in an RRC message and sends the RRC message to the source DU via F1AP signaling. The random access-free switching configuration information is included in the RRC message, for example, the random access-free switching configuration information is included in the RRC container. The F1AP signaling may be, for example, UE context modification request signaling (i.e., UEContext Modification Request signaling). If the first beam information is included in the RRC message in step 503-1, then the RRC message must also be included in the RRC message carrying the random access-free switching configuration information in step 504-1.

[0120] In another implementation manner, CU3 directly sends the random access-free switching configuration information to the source DU through F1AP signaling, for example, directly sends the random access-free switching configuration information to the source DU through UEContext Modification Request signaling.

[0121] 505-1, the source DU sends random access-free handover configuration information to the UE. Correspondingly, the UE receives the random access-free handover configuration information from the source DU.

[0122] The source DU transparently transmits the received random access-free handover configuration information to the UE. If the random access-free handover configuration information is included in the RRC message, the source DU directly transparently transmits the RRC message to the UE.

[0123] Based on the received random access-free switching configuration information, the UE can directly use the first beam information to communicate with the target cell without performing a random access process, thereby reducing the switching interruption time.

[0124] Method 2:

[0125] 501-2, CU3 determines first beam information based on the beam measurement information of the target cell of the UE. The first beam information is the beam information to be used by the UE to communicate with the target cell.

[0126] The beam measurement information of the target cell and the first beam information may refer to their specific description in step 501-1, which will not be repeated here. The process of CU3 determining the first beam information may refer to the process of the target DU determining the first beam information.

[0127] Before determining the first beam information, CU3 determines the target cell based on the neighboring cell measurement report sent by the source DU. The process of CU3 determining the target cell will be described in Figure 5A This is described in detail in step 500-d shown.

[0128] Optionally, in 502-2, CU3 sends the first beam information to the target DU. Correspondingly, the target DU receives the first beam information from CU3.

[0129] CU3 sends the first beam information to the target DU via F1AP signaling, and the target DU includes the first beam information in an RRC message. The F1AP signaling may be, for example, UE Context Setup Request signaling.

[0130] Optionally, in 503-2, the target DU sends the first beam information to CU3. Correspondingly, CU3 receives the first beam information from the target DU.

[0131] Based on the first beam information received through F1AP signaling, the target DU includes the first beam information in an RRC message, for example, includes the first beam information in an RRC container, and sends the RRC message to CU3 through F1AP signaling. The F1AP signaling may be, for example, UE Context Setup Response signaling.

[0132] The target DU sends the first beam information to CU3 so that CU3 generates a switching command.

[0133] 504-2, CU3 sends random access-free switching configuration information to the source DU. Correspondingly, the source DU receives the random access-free switching configuration information from CU3. The random access-free switching configuration information includes the first beam information.

[0134] CU3 generates a handover command based on the first beam information from the target DU, and the handover command may include random access-free handover configuration information, and the random access-free handover configuration information includes the first beam information. That is, CU3 generates a handover command instructing the UE not to perform a random access handover to distinguish it from a handover command for a non-random access-free handover, and the handover command for a non-random access-free handover instructs the UE to perform a random access procedure to access the target cell.

[0135] Optionally, the random access-free switching configuration information may further include TA indication information, where the TA indication information is used to instruct the UE to use the TA of the source cell to perform uplink synchronization with the target cell.

[0136] Optionally, the random access-free switching configuration information may further include uplink grant (UL Grant) indication information, where the UL Grant indication information is used to indicate resources, such as time-frequency resources, used by the UE for the first uplink data transmission.

[0137] In one implementation, CU3 includes the random access-free handover configuration information in an RRC message, and sends the RRC message to the source DU via F1AP signaling. The random access-free handover configuration information is included in the RRC message, for example, the random access-free handover configuration information is included in an RRC container. The F1AP signaling may be, for example, UEContext ModificationRequest signaling.

[0138] In another implementation manner, CU3 directly sends the random access-free switching configuration information to the source DU through F1AP signaling, for example, directly sends the random access-free switching configuration information to the source DU through UEContext Modification Request signaling.

[0139] 505-2, the source DU sends random access-free handover configuration information to the UE. Correspondingly, the UE receives the random access-free handover configuration information from the source DU.

[0140] The implementation process of step 505-2 can refer to the specific description of step 505-1, which will not be repeated here.

[0141] Figure 5In mode 1 and mode 2 of the illustrated embodiments, the UE can communicate directly with the target cell based on the first beam information, without performing a random access process (including beam selection) to access the target cell, thereby reducing the switching interruption time from the source cell to the target cell and helping to improve the communication performance of the terminal device.

[0142] See also Figure 5A , is a schematic diagram of a process for determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application, and the process may include but is not limited to the following steps:

[0143] 500-a, the mAB node updates the cell identifier.

[0144] Figure 5A The illustrated embodiment takes the case where the source DU and the target DU have established F1 connections with CU3 respectively as an example, that is, an Intra-CU scenario.

[0145] Exemplarily, when the mIAB node determines that there is a conflict in the cell identifier, it triggers the process of updating the cell identifier, that is, updating the cell identifier of the cell of the source DU. After the mIAB node moves, the cell identifier of its cell conflicts with the cell identifiers of the surrounding neighboring cells. For example, the cell identifier of cell 1 of the source DU is the same as the cell identifier of the neighboring cell (for example, cell 3), then the mIAB node can trigger the update of the cell identifier of cell 1. Among them, the cell identifier may include one or more of the following: cell global identifier (cell global identifier, CGI), physical cell identifier (physical cell identifier, PCI), new radio cell global identifier (newradiocell global identifier, NCGI), logical cell identifier, etc. In the embodiment of the present application, the cell identifier takes PCI as an example.

[0146] In one implementation, the target DU activates one of the at least one cells it manages, and uses the activated cell as the cell corresponding to the cell in the source DU where the cell identity conflict occurs after the cell identity is updated. Optionally, the source DU can also deactivate the conflicting cell. For example, the PCI#1 of cell 1 of the source DU is the same as the PCI#1 of the neighboring cell (cell 3). To avoid or reduce PCI conflicts, the target DU activates cell 2 of PCI#2 that it manages, and uses cell 2 as the cell corresponding to the cell 1 after the PCI is updated. The PCI of this cell is PCI#2, and the source DU can deactivate cell 1 after cell 2 is activated. This method takes a conflicting cell as an example. In actual applications, there may be multiple conflicting cells, and the mAB node can trigger the update of the cell identity of each conflicting cell.

[0147] 500-b, the source DU sends the UE's neighboring area measurement report to CU3. Correspondingly, CU3 receives the neighboring area measurement report from the source DU.

[0148] The UE sends the neighboring cell measurement report obtained by measuring the neighboring cell to the source DU, and the source DU sends it to CU3. The neighboring cell measurement report includes the cell identifier of at least one neighboring cell, the cell signal quality of at least one neighboring cell, and the beam measurement information of at least one neighboring cell. For the beam measurement information of a neighboring cell, it includes the beam identifier of at least one beam and the signal quality of at least one beam. The cell signal quality can be one or more of the following: RSRP, RSRQ, SINR, RSSI, etc.

[0149] Exemplarily, the source DU includes the neighboring cell measurement report in an RRC message, such as an RRC container, and sends the RRC message to CU3 via F1AP signaling. The F1AP signaling may be, for example, an uplink RRC message transfer (ie, UL RRC MessageTransfer) signaling.

[0150] 500-c, the source DU sends the first information to CU3. Correspondingly, CU3 receives the first information from the source DU. The first information includes the first cell identifier and the second cell identifier, and the first cell identifier and the second cell identifier have a corresponding relationship.

[0151] Among them, the first cell identifier is the cell identifier of the cell before the cell identifier is updated, that is, the cell identifier of the cell of the source DU before executing step 500-a; the second cell identifier is the cell identifier obtained after the cell identifier is updated, that is, after executing step 500-a, the cell identifier corresponding to the cell of the source DU after the cell identifier is updated. The first cell identifier may include one or more cell identifiers, and the second cell identifier may include one or more cell identifiers. For example, the correspondence between the first cell identifier and the second cell identifier may be shown in Table 1 below.

[0152] Table 1

[0153]

[0154]

[0155] Step 500-c is one implementation method, that is, the source DU sends the first cell identifier and the second cell identifier to CU3, which can be sent to CU3 explicitly or implicitly through F1AP signaling. In another implementation method, after the source DU updates the cell identifier, CU3 can obtain the cell identifiers before and after the update and the corresponding relationship between them through the F1 interface.

[0156] Optionally, step 500-c may also be executed by the target DU, that is, the target DU sends the first information to CU3.

[0157] The embodiment of the present application does not limit the order in which step 500-b and step 500-c are executed. For example, step 500-b may be executed first and then step 500-c, or step 500-c may be executed first and then step 500-b, or these two steps may be executed simultaneously.

[0158] 500-d, CU3 determines, based on the first information, that the UE needs to perform a random access-free switching process.

[0159] CU3 determines whether the source cell and the target cell of the UE are cells of the same mAB node based on the received first information and the neighboring cell measurement report. If it is determined that the source cell and the target cell are cells of the same mAB node, it is determined that the UE needs to perform a random access-free handover process.

[0160] Before determining whether the source cell and the target cell are cells of the same mAB node, the target cell and the cell identifier of the target cell are determined.

[0161] In one implementation, CU3 determines the target cell and the cell identifier of the target cell from at least one neighboring cell according to the neighboring cell measurement report. CU3 determines the target cell from at least one neighboring cell according to the neighboring cell measurement report, for example, selecting a cell with better cell signal quality from at least one neighboring cell as the target cell, or selecting a cell with better load balancing as the target cell, or selecting a cell with both better cell signal quality and better load balancing as the target cell.

[0162] In another implementation, CU3 selects at least one candidate neighboring area from at least one neighboring area based on the first information, the cell identifier of the candidate neighboring area and the cell identifier of the source cell are both in the first information, and determines the target cell and the cell identifier of the target cell from at least one candidate neighboring area. That is, CU3 selects a candidate neighboring area whose cell identifier is in the first information from at least one neighboring area based on the cell identifier in the first information and the cell identifier of at least one neighboring area. Determine the target cell from at least one candidate neighboring area, for example, select a candidate neighboring area with better cell signal quality as the target cell from at least one candidate neighboring area, or select a candidate neighboring area with better load balancing as the target cell, or select a candidate neighboring area with better cell signal quality and load balancing as the target cell. If the number of candidate neighboring areas is 1, then the candidate neighboring area is the target cell.

[0163] After determining the cell identifiers of the target cell and the target cell, CU3 determines whether the cell identifier of the source cell and the cell identifier of the target cell are in the first information. In the first information, it is determined that the source cell and the target cell are cells of the same mABnode; if the cell identifier of the source cell and / or the cell identifier of the target cell are not in the first information, it is determined that the source cell and the target cell are not cells of the same mAB node. CU3 can obtain the cell identifier of the source cell of the UE from the source DU through the F1 interface. Determine whether the cell identifier of the source cell and the cell identifier of the target cell are in the first information, for example, determine whether the PCI of the source cell is in Table 1 and whether the PCI of the target cell is in Table 1. It may be that the PCI of the source cell and the PCI of the target cell are PCIs in a row of Table 1; or, the PCI of the source cell is the PCI in the first column of Table 1, and the PCI of the target cell is the PCI in the second column of Table 1; or, the PCI of the source cell is the PCI in the second column of Table 1, and the PCI of the target cell is the PCI in the first column of Table 1. The cell identifier of the source cell may or may not have a corresponding relationship with the cell identifier of the target cell, depending on the specific situation.

[0164] When it is determined that the source cell and the target cell are cells of the same mAB node, CU3 determines that the UE needs to perform a random access-free handover process, and then executes Figure 5 Mode 1 or Mode 2 in the illustrated embodiment is used to reduce the handover interruption time. When it is determined that the source cell and / or the target cell are not cells of the same mAB node, CU3 determines that the UE needs to perform a random access handover process.

[0165] exist Figure 5A In the embodiment shown, after updating the cell identifier, the source DU sends first information indicating the first cell identifier and the second cell identifier to CU3. CU3 can determine whether the UE needs to perform a random access-free switching process based on the first information, and if so, perform Figure 5 Mode 1 or Mode 2 in the illustrated embodiment is used to reduce the switching interruption time.

[0166] Figure 5 and / or Figure 5AThe illustrated embodiment is based on CU3 obtaining the neighboring cell measurement report of the UE. If the source DU does not send the neighboring cell measurement report to CU3, then CU3 can select a cell identifier from the second cell identifier as the cell identifier of the target cell based on the cell identifier of the source cell, for example, select a PCI from the PCI shown in the second column of Table 1 as the PCI of the target cell. When selecting, it can be selected according to the corresponding relationship (for example, according to the corresponding relationship shown in the row of Table 1). For example, if the PCI of the source cell is PCI#1, then the cell identified by PCI#4 can be selected as the target cell; when selecting, it is also possible not to select according to the corresponding relationship. For example, if the PCI of the source cell is PCI#1, then the cell identified by PCI#5 or PCI#6 can be selected as the target cell. After determining the cell identifiers of the target cell and the target cell, CU3 can determine whether the UE needs to perform a random access-free switching process. Optionally, CU3 can also obtain the corresponding relationship between the beam identifier of the source cell and the beam identifier of the target cell from the source DU and / or the target DU.

[0167] In one implementation, CU3 may send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell to the target DU. The target DU may determine the first beam information based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell. For example, the target DU finds the beam identifier corresponding to the target cell based on the beam identifier of the beam used when the UE communicates with the source cell, includes it in the first beam information, and then executes steps 503-1 to 505-1.

[0168] In another implementation, CU3 can determine the first beam information based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell. For example, CU3 finds the beam identifier corresponding to the target cell based on the beam identifier of the beam used when the UE communicates with the source cell, includes it in the first beam information, and then executes steps 502-2 to 505-2.

[0169] Among them, the first beam information is the beam information to be used by the UE to communicate with the target cell. The beam identifier of the beam used by the UE when communicating with the source cell corresponds to the beam identifier of the target cell. It can be understood that the beam direction of the beam used by the UE when communicating with the source cell is the same as the beam direction of the beam identified by the beam identifier of the target cell.

[0170] Exemplarily, when CU3 obtains the neighboring area measurement report of the UE, CU3 can determine whether the UE needs to perform a random access-free switching process. When CU3 does not obtain the neighboring area measurement report of the UE, CU3 can also determine whether the UE needs to perform a random access-free switching process.

[0171] When CU3 determines that the UE needs to perform a random access-free handover procedure, Figure 5 Alternatively, CU3 may determine the first beam information without a neighboring area measurement report. To determine the first beam information without a neighboring area measurement report, at least one of the following methods may be used to reduce the switching interruption time and save UE power consumption.

[0172] The following are several methods for determining the first beam information proposed in this application:

[0173] Method (1), CU3 obtains the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell from the source DU. Exemplarily, the source DU can carry the above information through UEContext Setup Response signaling. CU3 then sends this information to the target DU. Exemplarily, CU3 can carry this information through UE Context Setup Request signaling. Based on this information, the target DU can determine that the beam identifier corresponds to the beam identifier of the target cell, thereby determining the first beam information, and then executing steps 503-1 to 505-1.

[0174] Method (2), CU3 obtains the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell from the source DU. Exemplarily, the source DU can carry the above information through UEContext Setup Response signaling. Based on this information, CU3 can determine that the beam identifier corresponds to the beam identifier of the target cell, thereby determining the first beam information, and then executing steps 502-2 to 505-2.

[0175] Method (3): The source DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell, thereby determining the first beam information and sending the first beam information to CU3. Exemplarily, the source DU can send the first beam information to CU3 through UE Context Modification Required, UE Context Modification Response or UL RRCMessage Transfer signaling, and then execute steps 502-2 to 505-2.

[0176] The above-mentioned methods (1) to (3) can be understood as the source DU and the target DU do not share the network configuration, that is, the configuration between the source DU and the target DU is a non-network sharing configuration. The following methods (4) to (7) can be understood as the source DU and the target DU share the network configuration, that is, the configuration between the source DU and the target DU is a network sharing configuration. The network sharing configuration information may include one or more of the corresponding relationship between the activated cell of the source DU and the activated cell of the target DU, the corresponding relationship between the beam identifier of the cell of the source DU and the beam identifier of the cell of the target DU, the context information when the UE communicates with the source cell, the beam identifier of the beam used when the UE communicates with the source cell, and the like. CU3 can obtain the network sharing configuration information from the source DU or the target DU.

[0177] In mode (4), the target DU is based on the UE identifier in the source cell obtained from CU3. Exemplarily, CU3 can send the UE identifier in the source cell to the target DU through UE Context Setup Request signaling, determine the beam identifier of the beam used when the UE communicates with the source cell, and then determine that the beam identifier corresponds to the beam identifier of the target cell, that is, determine the first beam information, and then execute steps 503-1 to 505-1. The UE identifier in the source cell refers to the identifier assigned to the communication between the UE and the source cell after the UE accesses the source cell. The identifier can be a combination of the cell identifier of the source cell and the cell radio network temporary identifier (C-RNTI). The cell identifier can be PCI or NCGI, etc. The C-RNTI can be allocated by the source DU to the UE after the UE accesses the source cell; the identifier can also be a combination of the gNB identifier to which the source cell belongs and the gNB-CU / DU UE F1AP ID. The gNB-CU / DU UE F1AP ID can be allocated by CU3 to the UE after the UE accesses the source cell; the identifier can also be other identifiers that can uniquely identify the UE in the source cell. The target DU determines the beam identifier of the beam used when the UE communicates with the source cell based on the identifier of the UE in the source cell and the cell identifier of the source cell. Among them, the cell identifier of the source cell can be obtained by the target DU from CU3. For example, CU3 can send the cell identifier of the source cell to the target DU through UE Context Setup Request signaling; or the target DU can query the cell identifier of the source cell based on the identifier of the UE in the source cell. Therefore, the target DU can determine that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell. The target DU can obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell through network sharing configuration.

[0178] Mode (5), the target DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the cell identifier of the source cell and the beam identifier of the beam used when the UE communicates with the source cell, thereby determining the first beam information, and then executing steps 503-1 to 505-1. Among them, the cell identifier of the source cell can be obtained by the target DU from CU3. Exemplarily, CU3 can send the cell identifier of the source cell to the target DU through UE Context Setup Request signaling, or the target DU can query the cell identifier of the source cell based on the source cell identifier for the UE in the source cell. The beam identifier of the beam used when the UE communicates with the source cell can be obtained by the target DU from the source DU. Therefore, the target DU can determine that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell. The target DU can obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell through the network sharing configuration. Optionally, the target DU can also obtain from the source DU the gNB-CU UE F1AP ID allocated by CU3 to the UE when communicating in the source cell, so as to associate the determined first beam information with the UE context returned by the target DU to CU3. Exemplarily, it can be associated with the UEContext Setup Response signaling sent by the target DU to CU3.

[0179] Method (6), CU3 obtains the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell based on the network sharing configuration information. CU3 can determine that the beam identifier corresponds to the beam identifier of the target cell based on this information, thereby determining the first beam information, and then executing steps 502-2 to 505-2. Optionally, CU3 determines the beam identifier of the beam used when the UE communicates with the source cell based on the identifier of the UE in the source cell and the cell identifier of the source cell, and then determines that the beam identifier corresponds to the beam identifier of the target cell. Optionally, CU3 determines that the beam identifier corresponds to the beam identifier of the target cell based on the cell identifier of the source cell and the beam identifier of the beam used when the UE communicates with the source cell.

[0180] Method (7), the source DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell, thereby determining the first beam information, and sending the first beam information to the target DU, and then executing steps 503-1 to 505-1. Optionally, the target DU can also obtain from the source DU the gNB-CU UE F1AP ID assigned by CU3 to the UE when communicating in the source cell, which is used to associate the determined first beam information with the UE context returned by the target DU to CU3. Exemplarily, it can be associated with the UE Context Setup Response signaling sent by the target DU to CU3.

[0181] As an optional embodiment, considering that the source cell and the target cell of the UE may be cells of the same DU, the above Figure 5 and Figure 5A The target DU shown in can also be regarded as the source DU in this case. The difference is Figure 5 The F1AP signaling involved in the interaction between the target DU and CU3 may be UEContext Modification Request signaling or UEContext Modification Response signaling; Figure 5A The method for updating the cell identifier of the mAB node may include: in one implementation, the source DU directly changes the conflicting cell identifier. For example, the PCI#1 of cell 1 of the source DU is the same as the PCI#1 of the neighboring cell (cell 3). To avoid or reduce PCI conflicts, the source DU changes the PCI#1 of cell 1 to PCI#2; in another implementation, the source DU activates another cell it manages, and updates the cell identifier of the activated cell as the cell corresponding to the conflicting cell. Optionally, the source DU can also deactivate the conflicting cell. For example, the PCI#1 of cell 1 of the source DU is the same as the PCI#1 of the neighboring cell (cell 3). To avoid or reduce PCI conflicts, the source DU activates the PCI#2 of cell 2 it manages, and updates cell 2 as the cell corresponding to cell 1 after the PCI is updated. The PCI of the cell is PCI#2. The source DU can deactivate cell 1 after cell 2 is activated.

[0182] See also Figure 6, is a flowchart of another communication method provided by an embodiment of the present application, which method may include method A, method B and method C, and any one of the three can be selected. It can be understood that in method A shown in steps 601-1 to 606-1, the first beam information is determined by the target DU; in method B shown in steps 601-2 to 606-2, the first beam information is determined by CU3; in method C shown in steps 601-3 to 607-3, the first beam information is determined by CU1. Figure 6 In the illustrated embodiment, the source DU establishes an F1 connection with CU1, and as the mAB node moves, the mAB node performs distributed unit migration, the target DU is activated, and the target DU establishes an F1 connection with CU3.

[0183] Method A:

[0184] 601-1, CU3 sends the beam measurement information of the target cell of the UE to the target DU. Correspondingly, the target DU receives the beam measurement information of the target cell of the UE from CU3.

[0185] Exemplarily, CU3 sends the beam measurement information of the target cell to the target DU via F1AP signaling, that is, the F1AP signaling includes the beam measurement information of the target cell. The F1AP signaling may be, for example, UE Context Setup Request signaling.

[0186] Among them, the beam measurement information of the target cell and the first beam information can refer to their specific description in step 501-1, which will not be repeated here.

[0187] The target cell may be determined by CU1 based on the neighboring cell measurement report and then notified to CU3. Fig. 6A A detailed description of this is given in the illustrated embodiment.

[0188] 602-1, the target DU determines first beam information based on the beam measurement information of the target cell. The first beam information is the beam information to be used by the UE to communicate with the target cell.

[0189] The target DU determines the first beam information to be used by the UE to communicate with the target cell based on the beam measurement information of the target cell. The first beam information includes the beam identifier of the first beam. For example, the beam measurement information of the target cell includes the signal quality of each SSB from SSB#1 to SSB#4, and the signal quality of SSB#3 is the best, then the beam corresponding to SSB#3 is selected as the first beam, and the beam identifier of the first beam is SSB#3. In other words, after the UE switches from the source cell to the target cell, it can directly use the first beam when communicating with the target cell, for example, using the beam corresponding to SSB#3 to send uplink data to the target cell. The UE does not need to perform measurements again, nor does it need to send a random access preamble to the target cell, which helps to reduce the switching interruption time.

[0190] 603-1, the target DU sends the first beam information to CU3.

[0191] After determining the first beam information, the target DU sends the first beam information to CU3 so that CU3 generates a switching command. In one implementation, the target DU includes the first beam information in an RRC message, for example, in an RRC container, and sends the RRC message to CU3 via F1AP signaling. In another implementation, the target DU directly sends the first beam information to CU3 via F1AP signaling, that is, the F1AP signaling explicitly includes the first beam information. The F1AP signaling may be, for example, UE Context Setup Response signaling.

[0192] 604-1, CU3 sends random access-free switching configuration information to CU1. Correspondingly, CU1 receives the random access-free switching configuration information from CU3. The random access-free switching configuration information includes first beam information.

[0193] In one implementation, CU3 may directly send the random access-free switching configuration information to CU1 through XnAP signaling, that is, the random access-free switching configuration information is included in the XnAP signaling, that is, the first beam information is included in the XnAP signaling.

[0194] In another implementation manner, CU3 includes the random access-free switching configuration information in an RRC message, for example, in an RRC container, and sends the RRC message to CU1 through XnAP signaling.

[0195] The XnAP signaling may be, for example, a handover request confirmation (ie, HO Request Acknowledge) signaling.

[0196] 605-1, CU1 sends random access-free handover configuration information to the source DU. Correspondingly, the source DU receives the random access-free handover configuration information from CU1.

[0197] 606-1, the source DU sends random access-free handover configuration information to the UE. Correspondingly, the UE receives the random access-free handover configuration information from the source DU.

[0198] The implementation process of step 605-1 and step 606-1 can refer to the specific description of step 504-1 and step 505-1, which will not be repeated here. The difference is that step 504-1 and step 505-1 are CU3 sending random access-free switching configuration information to UE through source DU, while step 605-1 and step 606-1 are CU1 sending random access-free switching configuration information to UE through source DU.

[0199] Method B:

[0200] 601-2, CU3 determines first beam information based on the beam measurement information of the target cell of the UE. The first beam information is the beam information to be used by the UE to communicate with the target cell.

[0201] The target cell may be determined by CU1 based on the neighboring cell measurement report and then notified to CU3. Fig. 6A A detailed description of this is given in the illustrated embodiment.

[0202] Optionally, in 602-2, CU3 sends the first beam information to the target DU. Correspondingly, the target DU receives the first beam information from CU3.

[0203] Optionally, in 603-2, the target DU sends the first beam information to CU3. Correspondingly, CU3 receives the first beam information from the target DU.

[0204] The implementation process of step 601 - 2 to step 603 - 2 can refer to the specific description of step 501 - 2 to step 503 - 2, which will not be repeated here.

[0205] 604-2, CU3 sends random access-free switching configuration information to CU1. Correspondingly, CU1 receives the random access-free switching configuration information from CU3. The random access-free switching configuration information includes the first beam information.

[0206] In one implementation, CU3 may directly send the random access-free switching configuration information to CU1 through XnAP signaling, that is, the random access-free switching configuration information is included in the XnAP signaling, that is, the first beam information is included in the XnAP signaling.

[0207] In another implementation manner, CU3 includes the random access-free switching configuration information in an RRC message, for example, in an RRC container, and sends the RRC message to CU1 through XnAP signaling.

[0208] The XnAP signaling may be, for example, HO Request Acknowledge signaling.

[0209] 605-2, CU1 sends random access-free handover configuration information to the source DU. Correspondingly, the source DU receives the random access-free handover configuration information from CU1.

[0210] 606-2, the source DU sends random access-free handover configuration information to the UE. Correspondingly, the UE receives the random access-free handover configuration information from the source DU.

[0211] The implementation process of step 605-2 and step 606-2 can refer to the specific description of step 504-1 and step 505-1, which will not be repeated here. The difference is that step 504-1 and step 505-1 are CU3 sending random access-free switching configuration information to UE through the source DU, while step 605-2 and step 606-2 are CU1 sending random access-free switching configuration information to UE through the source DU.

[0212] Method C:

[0213] 601-3, CU1 determines first beam information based on the beam measurement information of the target cell of the UE. The first beam information is the beam information to be used by the UE to communicate with the target cell.

[0214] The beam measurement information of the target cell and the first beam information may refer to their specific description in step 501-1, which will not be repeated here. The process of CU1 determining the first beam information may refer to the process of the target DU determining the first beam information.

[0215] The target cell may be determined by CU1 based on the neighboring cell measurement report, and CU1 may inform CU3 of the cell identifier of the target cell. Fig. 6A A detailed description of this is given in the illustrated embodiment.

[0216] Optionally, when CU3 determines that the UE needs to perform a random access-free switching process, CU3 sends indication information to CU1 through XnAP signaling, instructing CU1 to determine the first beam information.

[0217] 602-3, CU1 sends the first beam information to CU3. Correspondingly, CU3 receives the first beam information from CU1.

[0218] CU1 sends the first beam information to CU3 via XnAP signaling. The XnAP signaling may be, for example, a handover request (ie, HORequest) signaling.

[0219] Optionally, in 603-3, CU3 sends the first beam information to the target DU. Correspondingly, the target DU receives the first beam information from CU3.

[0220] Optionally, in 604-3, the target DU sends the first beam information to CU3. Correspondingly, CU3 receives the first beam information from the target DU.

[0221] The implementation process of step 603-3 and step 604-3 can refer to the specific description of step 502-2 and step 503-2, which will not be repeated here.

[0222] 605-3, CU3 sends random access-free switching configuration information to CU1. Correspondingly, CU1 receives the random access-free switching configuration information from CU3. The random access-free switching configuration information includes the first beam information.

[0223] In one implementation, CU3 may directly send the random access-free switching configuration information to CU1 through XnAP signaling, that is, the random access-free switching configuration information is included in the XnAP signaling, that is, the first beam information is included in the XnAP signaling.

[0224] In another implementation manner, CU3 includes the random access-free switching configuration information in an RRC message, for example, in an RRC container, and sends the RRC message to CU1 through XnAP signaling.

[0225] The XnAP signaling may be, for example, HO Request Acknowledge signaling.

[0226] 606-3, CU1 sends random access-free handover configuration information to the source DU. Correspondingly, the source DU receives the random access-free handover configuration information from CU1.

[0227] 607-3, the source DU sends random access-free handover configuration information to the UE. Correspondingly, the UE receives the random access-free handover configuration information from the source DU.

[0228] The implementation process of step 606-3 and step 607-3 can refer to the specific description of step 504-1 and step 505-1, which will not be repeated here. The difference is that step 504-1 and step 505-1 are CU3 sending random access-free switching configuration information to UE through the source DU, while step 606-3 and step 607-3 are CU1 sending random access-free switching configuration information to UE through the source DU.

[0229] Figure 6In the methods A, B and C of the illustrated embodiments, the UE can communicate directly with the target cell based on the first beam information without performing a random access process (including beam selection) to access the target cell, thereby reducing the switching interruption time from the source cell to the target cell and helping to improve the communication performance of the terminal device.

[0230] See also Fig. 6A , is another flow chart of determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application, and the process may include but is not limited to the following steps:

[0231] 701, the source DU sends the cell identifier of the first cell and the cell identifier of the second cell to CU1. Correspondingly, CU1 receives the cell identifier of the first cell and the cell identifier of the second cell from the source DU. The cell identifier of the first cell has a corresponding relationship with the cell identifier of the second cell.

[0232] Among them, the first cell is a cell managed and activated by the source DU, that is, the cell activated when the source DU establishes an F1 connection with CU1; the second cell is a cell managed and activated by the target DU, that is, the cell activated when the target DU establishes an F1 connection with CU3. The number of the first cell and the second cell can be one or more. The correspondence between the cell identifier of the first cell and the cell identifier of the second cell is used to describe the correspondence between the cell activated by the source DU and the cell activated by the target DU.

[0233] The source DU may send the cell identifier of the first cell and the cell identifier of the second cell to CU1 through the F1 connection between the source DU and CU1.

[0234] Optionally, the source DU may also send the cell identifier of the source cell of the UE to CU1 via the F1 connection between the source DU and CU1. The embodiment of the present application does not limit the order of sending the cell identifier of the source cell and executing step 701.

[0235] Optionally, the source DU may also send the UE's neighboring cell measurement report to CU1 via the F1 connection between the source DU and CU1. The embodiment of the present application does not limit the order of sending the cell identifier of the source cell, sending the UE's neighboring cell measurement report, and executing step 701.

[0236] Method (a):

[0237] 702a: CU1 determines, based on the cell identifier of the first cell and the cell identifier of the second cell, that the source cell and the target cell of the UE are cells of the same mAB node.

[0238] Before determining that the source cell and the target cell of the UE are cells of the same mAB node, CU1 determines the target cell and the cell identifier of the target cell.

[0239] In one implementation, CU1 determines a target cell and a cell identifier of the target cell from at least one neighboring cell according to the neighboring cell measurement report.

[0240] In another implementation, CU1 selects at least one candidate neighboring cell from at least one neighboring cell based on the cell identifier of the first cell and the cell identifier of the second cell, the cell identifier of the candidate neighboring cell and the cell identifier of the source cell are in the cell identifier of the first cell and / or the cell identifier of the second cell, and determines the target cell and the cell identifier of the target cell from at least one candidate neighboring cell.

[0241] After determining the cell identifiers of the target cell and the target cell, CU1 determines whether the cell identifier of the source cell and the cell identifier of the target cell are in the cell identifier of the first cell and the cell identifier of the second cell. If they are in the cell identifier of the first cell and the cell identifier of the second cell, it is determined that the source cell and the target cell are cells of the same mAB node; otherwise, it is determined that the source cell and the target cell are not cells of the same mAB node.

[0242] 703a, CU1 sends first information to CU3. Correspondingly, CU3 receives the first information from CU1. The first information indicates that the UE needs to perform a random access-free switching process.

[0243] After determining that the source cell and the target cell of the UE are cells of the same mAB node, CU1 sends the first information to CU3. CU1 may directly send the first information to CU3 through XnAP signaling. The XnAP signaling may be, for example, HO Request signaling.

[0244] Optionally, the first information also includes TA indication information (i.e., same-TA indication information), which is used to instruct the UE to use the TA of the source cell to perform uplink synchronization with the target cell. Optionally, the first information may be TA indication information (i.e., same-TA indication information), that is, the TA indication information not only instructs the UE to use the TA of the source cell to perform uplink synchronization with the target cell, but also indicates that the UE needs to perform a random access-free switching process. It is understandable that the TA indication information may implicitly indicate that the UE needs to perform a random access-free switching process.

[0245] Optionally, the first information also includes beam measurement information of the target cell. For example, CU1 may include the beam measurement information of the target cell in the RRC message.

[0246] Optionally, the first information further includes first beam information determined by CU1. For example, CU1 may include the first beam information in an RRC message.

[0247] 704a, CU3 determines that the UE needs to perform a random access-free handover process.

[0248] Based on the received first information indicating that the UE needs to perform the random access-free switching process, CU3 can determine that the UE needs to perform the random access-free switching process. It can be understood that the first information indicating that the UE needs to perform the random access-free switching process is a suggestion of CU1, and CU3 can adopt it or not. If it is adopted, it is determined that the UE needs to perform the random access-free switching process, and if it is not adopted, it is determined that the UE needs to perform the non-random access-free switching process.

[0249] Method (b):

[0250] 702b: CU1 determines, based on the cell identifier of the first cell and the cell identifier of the second cell, that the source cell and the target cell of the UE are cells of the same mIAB node.

[0251] The implementation process of step 702b can refer to the specific description of step 702a, which will not be repeated here.

[0252] 703b, CU1 sends first information to CU3. Correspondingly, CU3 receives the first information from CU1. The first information indicates that the source cell and the target cell of the UE are cells of the same mAB node.

[0253] After determining that the source cell and the target cell of the UE are cells of the same mAB node, CU1 sends the first information to CU3. CU1 may directly send the first information to CU3 through XnAP signaling. The XnAP signaling may be, for example, HO Request signaling.

[0254] Optionally, the first information further includes TA indication information, indicating the UE to use the TA of the source cell to perform uplink synchronization with the target cell. Optionally, the first information may be the TA indication information, which may implicitly indicate that the source cell and the target cell of the UE are cells of the same mAB node.

[0255] 704b, in response to the source cell and the target cell of the UE being cells of the same mAB node, CU3 determines that the UE needs to perform a random access-free handover procedure.

[0256] It can be understood that CU1 directly informs CU3 that the source cell and the target cell of the UE are cells of the same mAB node, so that CU3 can directly determine that the UE needs to perform a random access-free handover process.

[0257] Method (c):

[0258] 702c, CU1 sends the first information to CU3. Correspondingly, CU3 receives the first information from CU1.

[0259] The first information indicates a cell identifier of the first cell and a cell identifier of the second cell. The cell identifier of the first cell and the cell identifier of the second cell have a corresponding relationship.

[0260] Optionally, CU1 also sends the cell identifier of the source cell to CU3. Exemplarily, CU1 first sends the first information to CU3, for example, sending the first information to CU3 through Xn Setup Request (i.e., Xn Setup Request) / next generation radio access network (NG-RAN) node configuration update (i.e., NG-RAN node Configuration Update) signaling, and then sends the cell identifier of the source cell to CU3, for example, sending the cell identifier of the source cell to CU3 through HORequest signaling. Exemplarily, CU1 sends the cell identifier of the source cell and part of the first information to CU3, for example, sending the cell identifier of the source cell and part of the first information to CU3 through HORequest signaling, and the part of the first information includes at least the cell identifier of the second cell corresponding to the source cell.

[0261] Optionally, CU1 also sends the cell identifier of the target cell to CU3. The process of CU1 determining the target cell can be referred to the specific description in step 702a, which will not be repeated here. It may be carried in the first information or may not be carried in the first information.

[0262] Optionally, CU1 also sends beam measurement information of the target cell to CU3. The beam measurement information may be carried in the first information or may not be carried in the first information.

[0263] Optionally, CU1 also sends the first beam information to CU3.

[0264] 703c: CU3 determines, based on the cell identifier of the first cell and the cell identifier of the second cell, that the source cell and the target cell of the UE are cells of the same mAB node.

[0265] Step 703c is similar to step 702b, except that one is executed by CU1 and the other is executed by CU3. Please refer to the detailed description of step 702b, which will not be repeated here.

[0266] 704c, in response to the source cell and the target cell of the UE being cells of the same mAB node, CU3 determines that the UE needs to perform a random access-free handover procedure.

[0267] exist Fig. 6A In the embodiment shown, CU3 can determine based on the first information that the UE needs to perform a random access-free switching process, and perform Figure 6Method A, method B or method C in the illustrated embodiment is used to reduce the switching interruption time.

[0268] See also Figure 6B , is another flow chart of determining that a UE needs to perform a random access-free switching process provided by an embodiment of the present application, and the process may include but is not limited to the following steps:

[0269] 701d, the target DU sends first information to CU3. Correspondingly, CU3 receives the first information from the target DU. The first information indicates the cell information of the first cell.

[0270] The cell information of the first cell includes a cell identifier, and may also include a carrier identifier, a tracking area code (TAC), a radio access network area code (RANAC), etc. The first cell is a cell managed and activated by the source DU, that is, a cell activated when the source DU establishes an F1 connection with CU1. The target DU can obtain the cell information of the first cell from the source DU.

[0271] The target DU may send the cell information of the first cell to CU3 via the F1 connection between the target DU and CU3.

[0272] Optionally, CU3 obtains the cell identifier of the source cell of the UE from CU1.

[0273] Optionally, CU3 also obtains the cell identifier of the target cell of the UE from CU1. The cell identifier of the target cell and the cell identifier of the source cell may be obtained simultaneously, or the cell identifier of the source cell may be obtained first and then the cell identifier of the target cell may be obtained.

[0274] 702d, CU3 determines, based on the cell information of the first cell, that the source cell and the target cell of the UE are cells of the same mIABnode.

[0275] CU3 receives the cell information of the first cell from the target DU, indicating that there is a corresponding relationship between the first cell and the target DU. If the cell identifier of the source cell is in the cell information of the first cell, then there is a corresponding relationship between the source cell and the target DU. If there is a corresponding relationship between the source cell and the target DU and the cell identifier of the target cell is in the cell information of the second cell, then CU3 can determine that there is a corresponding relationship between the source cell and the target cell, that is, the source cell and the target cell are cells of the same mAB node. Among them, the second cell is a cell managed and activated by the target DU, that is, the cell activated when the target DU establishes an F1 connection with CU3.

[0276] 703d, in response to the source cell and the target cell of the UE being cells of the same mAB node, CU3 determines that the UE needs to perform a random access-free handover procedure.

[0277] exist Figure 6B In the embodiment shown, CU3 can determine that the UE needs to perform a random access-free switching process based on the cell information of the first cell, and perform Figure 6 Method A, method B or method C in the illustrated embodiment is used to reduce the switching interruption time.

[0278] As an optional embodiment, the first information may indicate the cell identifier of the first cell and the cell identifier of the second cell. The cell identifier of the first cell corresponds to the cell identifier of the second cell. The target DU may send the cell identifier of the first cell and the cell identifier of the second cell to CU3, and then CU3 may determine that the source cell and the target cell of the UE are cells of the same mIAB node based on the cell identifier of the first cell and the cell identifier of the second cell, and then determine that the UE needs to perform a random access-free switching process. Among them, the process in which CU3 determines that the source cell and the target cell of the UE are cells of the same mIAB node based on the cell identifier of the first cell and the cell identifier of the second cell can be referred to the specific description of step 703c, which will not be repeated here.

[0279] As an optional embodiment, when the source DU and the target DU share the network configuration, CU3 can also determine the cell identifier of the source cell of the UE based on the identifier of the UE in the source cell and the network sharing configuration information obtained from the target DU, such as the context information when the UE communicates with the source cell. For example, the target DU can send the network sharing configuration information to CU3 through the F1 establishment request (i.e., F1Setup Request) signaling. Then CU3 determines whether the source cell and the target cell of the UE are cells of the same mAB node based on the cell identifier of the first cell and the cell identifier of the second cell. The identifier of the UE in the source cell can be sent by CU1 to CU3. For example, CU1 can send the cell identifier of the source cell to CU3 through HO Request signaling. Alternatively, CU3 further sends the UE's identifier in the source cell and the identifier of the target cell obtained from CU1 to the target DU, and the target DU determines the cell identifier of the UE's source cell based on the network sharing configuration information, and then judges whether the UE's source cell and target cell are cells of the same mAB node based on the correspondence between the activated cell of the source DU and the activated cell of the target DU (that is, the correspondence between the first cell and the second cell), and then informs CU3 of the judgment result. Exemplarily, the judgment result can be carried to CU3 via UE Context Setup Response signaling.

[0280] Figure 6 The embodiment shown, Fig. 6A The embodiment shown or Figure 6B At least one of the illustrated embodiments is based on CU1 obtaining the neighboring cell measurement report of the UE. If the source DU does not send the neighboring cell measurement report to CU1, then CU3 and the target DU do not obtain the neighboring cell measurement report. CU1 can select a cell from the second cell as the target cell based on the cell identifier of the source cell, that is, select a cell from the cell of the target DU as the target cell. After determining the cell identifiers of the target cell and the target cell, CU1 can determine whether the UE needs to perform a random access-free switching process. In one implementation, CU1 can also obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell from the source DU and / or the target DU.

[0281] For method A, CU1 can also send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell to CU3, and CU3 sends the correspondence to the target DU. The target DU determines the first beam information based on the correspondence. For example, the target DU selects the beam identifier corresponding to the target cell based on the beam identifier of the beam used when the UE communicates with the source cell, includes it in the first beam information, and then executes steps 603-1 to 606-1.

[0282] For method B, CU1 may also send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell to CU3. CU3 determines the first beam information based on the correspondence and then executes steps 602-2 to 606-2.

[0283] For method C, CU1 determines the first beam information based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell, and then executes steps 602-3 to 607-3.

[0284] In another implementation, the target DU may also send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell to CU3, and CU3 may determine the first beam information based on the correspondence, and then execute steps 602-2 to 606-2. Alternatively, the target DU may also determine the first beam information based on the correspondence, and then execute steps 603-1 to 606-1.

[0285] Among them, the first beam information is the beam information to be used by the UE to communicate with the target cell. The beam identifier of the beam used by the UE when communicating with the source cell corresponds to the beam identifier of the target cell. It can be understood that the beam direction of the beam used by the UE when communicating with the source cell is the same as the beam direction of the beam identified by the beam identifier of the target cell.

[0286] Exemplarily, when CU1 obtains the neighboring area measurement report of the UE, CU1 can determine whether the UE needs to perform a random access-free switching process; when CU1 does not obtain the neighboring area measurement report of the UE, CU1 can also determine whether the UE needs to perform a random access-free switching process.

[0287] When CU1 determines that the UE needs to perform a random access-free handover procedure, it can execute Figure 6 Alternatively, CU1 may determine the first beam information without a neighboring cell measurement report. To determine the first beam information without a neighboring cell measurement report, at least one of the following methods may be used to reduce the switching interruption time and save UE power consumption.

[0288] The following are several methods for determining the first beam information proposed in this application:

[0289] Method (1), CU1 can also obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell from the source DU. For example, the source DU can carry the above information through UEContext Setup Response signaling.

[0290] For method A, CU1 may also send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell to CU3. Exemplarily, CU1 may carry the above information through HORequest signaling. CU3 then sends this information to the target DU. Exemplarily, CU3 may carry this information through UEContext Setup Request signaling. The target DU determines the first beam information based on the correspondence and the beam identifier of the beam used when the UE communicates with the source cell. For example, the target DU selects the beam identifier corresponding to the target cell based on the beam identifier of the beam used when the UE communicates with the source cell, includes it in the first beam information, and then executes steps 603-1 to 606-1.

[0291] For mode B, CU1 may also send the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell to CU3. For example, CU1 may carry the above information through HORequest signaling. CU3 determines the first beam information based on the correspondence and the beam identifier of the beam used when the UE communicates with the source cell, and then executes steps 602-2 to 606-2.

[0292] For method C, CU1 determines the first beam information based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell, and then executes steps 602-3 to 607-3.

[0293] Method (two): the source DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell, thereby determining the first beam information and sending the first beam information to CU1. Exemplarily, the source DU can send the first beam information to CU1 through UE Context Modification Required, UE Context Modification Response or UL RRCMessage Transfer signaling, and then execute steps 602-3 to 607-3.

[0294] The above-mentioned methods (1) and (2) can be understood as the source DU and the target DU do not share the network configuration. The following methods (3) to (7) can be understood as the source DU and the target DU share the network configuration.

[0295] Method (three), the target DU determines the beam identifier of the beam used when the UE communicates with the source cell based on the identifier of the UE in the source cell obtained from CU3 (CU3 obtains it from CU1, for example, through HO Request signaling), and then determines that the beam identifier corresponds to the beam identifier of the target cell, that is, determines the first beam information, and then executes steps 603-1 to 606-1. The target DU determines the beam identifier of the beam used when the UE communicates with the source cell based on the identifier of the UE in the source cell and the cell identifier of the source cell. Among them, the cell identifier of the source cell can be obtained by the target DU from CU3 (CU3 obtains it from CU1), or the target DU can query the cell identifier of the source cell according to the identifier allocated by the source cell to the UE. Therefore, the target DU can determine that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell. The target DU can obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell through network sharing configuration.

[0296] Mode (four), the target DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the cell identifier of the source cell and the beam identifier of the beam used when the UE communicates with the source cell, thereby determining the first beam information, and then executing steps 603-1 to 606-1. Among them, the cell identifier of the source cell can be obtained by the target DU from CU3 (CU3 obtains it from CU1, for example, through HO Request signaling). Exemplarily, CU3 can send the cell identifier of the source cell to the target DU through UE Context SetupRequest signaling, or the target DU can query the cell identifier of the source cell according to the source cell for the UE in the source cell. The beam identifier of the beam used when the UE communicates with the source cell can be obtained by the target DU from the source DU. Therefore, the target DU can determine that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell. The target DU can obtain the correspondence between the beam identifier of the source cell and the beam identifier of the target cell through the network sharing configuration. Optionally, the target DU can also obtain from the source DU the NG-RAN node UE XnAP ID allocated by CU1 to the UE when communicating in the source cell, so as to associate the determined first beam information with the UE context returned by the target DU to CU3. Exemplarily, it can be associated with the UE Context Setup Response signaling sent by the target DU to CU3.

[0297] Method (five), CU1 obtains the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell based on the network sharing configuration information, and sends this information to CU3. CU3 determines the first beam information based on the correspondence and the beam identifier of the beam used when the UE communicates with the source cell, and then executes steps 602-2 to 606-2. Optionally, CU3 obtains the UE's identifier in the source cell and the cell identifier of the source cell from CU1, and determines the beam identifier of the beam used when the UE communicates with the source cell based on this information, and then determines that the beam identifier corresponds to the beam identifier of the target cell. Optionally, CU3 obtains the cell identifier of the source cell and the beam identifier of the beam used when the UE communicates with the source cell from CU1, and determines that the beam identifier corresponds to the beam identifier of the target cell based on this information.

[0298] Method (six), CU1 obtains the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell based on the network sharing configuration information, and determines the first beam information based on this information, and then executes steps 602-3 to 607-3. Optionally, CU1 determines the beam identifier of the beam used when the UE communicates with the source cell based on the identifier of the UE in the source cell and the cell identifier of the source cell, and then determines that the beam identifier corresponds to the beam identifier of the target cell. Optionally, CU1 determines that the beam identifier corresponds to the beam identifier of the target cell based on the cell identifier of the source cell and the beam identifier of the beam used when the UE communicates with the source cell.

[0299] Method (seven): the source DU determines that the beam identifier corresponds to the beam identifier of the target cell based on the correspondence between the beam identifier of the source cell and the beam identifier of the target cell and the beam identifier of the beam used when the UE communicates with the source cell, and sends the beam identifier of the target cell to the target DU, and then executes 603-1 to 606-1. Optionally, the target DU can also obtain from the source DU the NG-RAN node UE XnAPID allocated by CU1 to the UE when communicating in the source cell, which is used to associate the determined first beam information with the UE context returned by the target DU to CU3. Exemplarily, it can be associated with the UE Context Setup Response signaling sent by the target DU to CU3.

[0300] Figure 6 , Fig. 6A as well as Figure 6BThe illustrated embodiment is based on the existence of an Xn interface between CU1 and CU3. If there is no Xn interface between CU1 and CU3, the UE can be instructed to perform a random access-free switching process through a switching process based on the NG interface. That is, the signaling exchanged between CU1 and CU3 can be forwarded through a core network element (e.g., access and mobility management function (AMF)). Exemplarily, for the content sent by CU1 to CU3 through HORequest signaling, CU1 first sends the content to AMF, for example, sends the content to AMF through a NGAP switching required (i.e., HO Required) message, and then AMF sends the content to CU3, for example, sends the content to CU3 through a NGAP HORequest message. Exemplarily, for the content sent by CU3 to CU1 through HO Request Acknowledge signaling, CU3 first sends the content to AMF, for example, sends the content to AMF through a NGAP HO Request Acknowledge message, and then AMF sends the content to CU1, for example, sends the content to CU1 through a NGAP switching command (i.e., HOCommand) message.

[0301] The present application provides a communication device that can be used to implement the functions of the above-mentioned CU3, CU1 or target DU. The communication device can be CU3, CU1 or target DU. The communication device includes a unit corresponding to the method / operation / step / action performed by CU3, CU1 or target DU in the above-mentioned method embodiment. The unit can be a hardware circuit, or software, or a combination of a hardware circuit and software. Figure 7 , Figure 7 A schematic diagram of the structure of a communication device 800 according to an embodiment of the present application is shown. The communication device 800 may include an interface unit 801 and a processing unit 802. Specifically, the processing unit 802 is used to process signaling and / or data, the signaling and / or data may be data received by the interface unit 801, and the processed signaling and / or data may also be sent by the interface unit 801;

[0302] In one implementation, when the communication device 800 is CU3, wherein:

[0303] The processing unit 802 is configured to determine first beam information to be used by the terminal device for communication with the target cell, where the first beam information includes a beam identifier of the first beam; the communication of the terminal device is to be switched from the source cell to the target cell, where the source cell and the target cell of the terminal device are cells of the relay node;

[0304] The interface unit 801 is used to send random access-free switching configuration information to the terminal device, where the random access-free switching configuration information includes first beam information.

[0305] In this embodiment, for the specific implementation of the above interface unit 801 and the processing unit 802, please refer to Figure 5 , Figure 5A , Figure 6 , Fig. 6A or Figure 6B The specific implementation steps of CU3 will not be repeated here.

[0306] In another embodiment, the Figure 8 When the communication device shown is CU1, wherein:

[0307] The processing unit 802 is configured to determine first beam information to be used by the terminal device for communication with the target cell, where the first beam information includes a beam identifier of the first beam; the communication of the terminal device is to be switched from the source cell to the target cell, where the source cell and the target cell of the terminal device are cells of the relay node;

[0308] The interface unit 801 is used to send random access-free switching configuration information to the terminal device, where the random access-free switching configuration information includes first beam information.

[0309] In this embodiment, for the specific implementation of the above interface unit 801 and the processing unit 802, please refer to Figure 6 , Fig. 6A or Figure 6B The specific implementation steps of CU1 will not be repeated here.

[0310] In yet another embodiment, the Figure 8 When the communication device shown is a target DU, wherein:

[0311] The interface unit 801 is configured to receive beam measurement information of a target cell of a terminal device from a first host node, where the beam measurement information includes a beam identifier of at least one beam;

[0312] Processing unit 802 is used to determine the first beam information to be used by the terminal device to communicate with the target cell based on the beam measurement information of the target cell, the first beam information including the beam identifier of the first beam, and at least one beam including the first beam; and send the first beam information to the first host node.

[0313] or,

[0314] The interface unit 801 is configured to receive first beam information from a first host node, the first beam information including a beam identifier of the first beam, and the first beam information is beam information to be used by the terminal device to communicate with the target cell; and send the first beam information to the first host node, the first beam information being included in an RRC message. The RRC message is included in F1AP signaling.

[0315] In this embodiment, for the specific implementation of the above interface unit 801 and the processing unit 802, please refer to Figure 5 , Figure 5A , Figure 6 , Fig. 6A or Figure 6B The specific implementation steps of the target DU will not be repeated here.

[0316] like Figure 8 A communication device 900 provided in an embodiment of the present application is shown, which is used to implement the functions of the above-mentioned CU3, CU1 or target DU. The device can be a communication device or a device used in a communication device, and the communication device can be CU3, CU1 or target DU. The device used in the communication device can be a chip system or a chip in the communication device. Among them, the chip system can be composed of chips, or it can include chips and other discrete devices.

[0317] The communication device 900 includes at least one processor 910 for implementing the processing functions of the device (e.g., CU3, CU1, or target DU) in the method provided in an embodiment of the present application. The communication device 900 may also include a communication interface 920 for implementing the transceiver operation of the device (e.g., CU3, CU1, or target DU) in the method provided in an embodiment of the present application. In an embodiment of the present application, the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface for communicating with other devices via a transmission medium. For example, the communication interface 920 is used for the device in the communication device 900 to communicate with other devices. The processor 910 uses the communication interface 920 to send and receive data, and is used to implement the method described in the above method embodiment.

[0318] The communication device 900 may also include at least one memory 930 for storing program instructions and / or data. The memory 930 is coupled to the processor 910. The coupling in the embodiment of the present application is an indirect coupling or communication connection between devices, units or modules, which may be electrical, mechanical or other forms, and is used for information exchange between devices, units or modules. The processor 910 may operate in conjunction with the memory 930. The processor 910 may execute program instructions stored in the memory 930. At least one of the at least one memory may be included in the processor.

[0319] The specific connection medium between the communication interface 920, the processor 910 and the memory 930 is not limited in the embodiment of the present application. Figure 8 The memory 930, the processor 910 and the communication interface 920 are connected via a bus. Figure 8 The connections between the other components are shown in bold lines, which are only for illustration and are not intended to be limiting. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0320] When the communication device 900 is specifically a device for a device (e.g., CU3, CU1, or a target DU), for example, when the communication device 900 is specifically a chip or a chip system, the communication interface 920 may output or receive a baseband signal. When the communication device 900 is specifically a device (e.g., CU3, CU1, or a target DU), the communication interface 920 may output or receive a radio frequency signal. In an embodiment of the present application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array, or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in conjunction with the embodiments of the present application may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0321] When the above-mentioned communication device 900 is a module applied to a base station, the base station module implements the functions of the base station in the above-mentioned method embodiment. The base station module receives information from other modules in the base station (such as a radio frequency module or an antenna), and the information is sent by the terminal to the base station; or, the base station module sends information to other modules in the base station (such as a radio frequency module or an antenna), and the information is sent by the base station to the terminal. The base station module here can be a baseband chip of a base station, or a CU, DU or other module, or a device under the O-RAN architecture, such as an open CU, an open DU and other devices.

[0322] It should be noted that the above-mentioned communication interface 920 can be used to execute the function of the above-mentioned interface unit 801, and the above-mentioned processor 910 can be used to execute the function of the above-mentioned processing unit 802, which will not be repeated here.

[0323] When the above-mentioned communication device is a chip applied to CU3, the chip implements the function of CU3 in the above-mentioned method embodiment, and the chip receives information from other devices; or, the chip sends information to other devices.

[0324] When the communication device is a chip applied to CU1, the chip implements the function of CU1 in the above method embodiment. The chip receives information from other devices; or the chip sends information to other devices.

[0325] When the communication device is a chip applied to the target DU, the chip implements the function of the target DU in the above method embodiment. The chip receives information from other devices (such as UE or CU); or the chip sends information to other devices.

[0326] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0327] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable ROM (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in an access network device or a terminal. Of course, the processor and the storage medium can also be present in a terminal or an access network device as discrete components.

[0328] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instruction is loaded and executed on a computer, the process or function described in the embodiment of the present application is executed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer program or instruction may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a tape; it may also be an optical medium, such as a DVD; it may also be a semiconductor medium, such as a solid state drive (SSD).

[0329] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0330] It is understood that the various numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic.

[0331] An embodiment of the present application further provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed, the method executed by CU3, CU1 or target DU in the above method embodiment is implemented.

[0332] An embodiment of the present application further provides a computer program product, which includes a computer program. When the computer program is executed, the method executed by CU3, CU1 or target DU in the above method embodiment is implemented.

[0333] The embodiment of the present application further provides a communication system, the communication system comprising CU3, CU1 or target DU. Each device is used to execute the method executed by each device in the above method embodiment.

[0334] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0335] The descriptions of the various embodiments provided in this application can refer to each other, and the descriptions of the various embodiments have different focuses. For parts that are not described in detail in a certain embodiment, refer to the relevant descriptions of other embodiments. For the convenience and simplicity of description, for example, the functions of the various devices and equipment provided in the embodiments of this application and the steps of execution can refer to the relevant descriptions of the method embodiments of this application, and the various method embodiments and the various device embodiments can also refer to, combine or quote each other.

[0336] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A communication method, characterized in that: The method comprises: Determine first beam information to be used by the terminal device for communication with the target cell, the first beam information including a beam identifier of the first beam; the communication of the terminal device will be switched from a source cell to the target cell, the source cell and the target cell being cells of relay nodes; Send random access-free switching configuration information to the terminal device, where the random access-free switching configuration information includes the first beam information.

2. The method according to claim 1, characterized in that Before determining the first beam information to be used by the terminal device to communicate with the target cell, the method further includes: Receive beam measurement information of the target cell from a source distributed unit DU; the beam measurement information includes a beam identifier of at least one beam, and the at least one beam includes the first beam; the source DU belongs to the relay node.

3. The method according to claim 2, characterized in that The determining the first beam information to be used by the terminal device to communicate with the target cell includes: The first beam information is determined based on the beam measurement information of the target cell.

4. The method according to claim 2, characterized in that: The determining the first beam information to be used by the terminal device to communicate with the target cell includes: Sending beam measurement information of the target cell to a target DU, where the target DU belongs to the relay node; The first beam information is received from the target DU.

5. The method according to claim 1 or 2, characterized in that: The determining the first beam information to be used by the terminal device to communicate with the target cell includes: The first beam information is received from a second host node.

6. The method according to claim 3 or 5, characterized in that: The method further comprises: Sending the first beam information to the target DU; the target DU belongs to the relay node; Receive the first beam information from the target DU; the first beam information is included in an RRC message.

7. The method according to any one of claims 1 to 6, characterized in that: The sending the random access-free switching configuration information to the terminal device includes: Sending the random access-free switching configuration information to the terminal device through the source DU; Alternatively, the random access-free switching configuration information is sent to the terminal device through the second host node and the source DU; The source DU belongs to the relay node.

8. The method according to any one of claims 1 to 7, characterized in that: Before determining the first beam information to be used by the terminal device to communicate with the target cell, the method further includes: receiving a first message; Based on the first information, it is determined that the terminal device needs to perform a random access-free switching process.

9. The method according to claim 8, characterized in that The first information comes from the second host node, and the first information indicates that the terminal device needs to perform the random access-free switching process.

10. The method according to claim 8, characterized in that The first information comes from a source DU or a second host node, and the first information is used to indicate that a source cell of the terminal device and a target cell of the terminal device are cells of the relay node; the source DU belongs to the relay node.

11. The method according to claim 10, characterized in that The first information comes from the second host node, and the method further includes: A cell identifier of the source cell and a cell identifier of the target cell are received from the second donor node.

12. The method according to claim 8, characterized in that The first information comes from a target DU, the target DU belongs to the relay node, the first information indicates cell information of a first cell, and the first cell is a cell activated when the relay node is connected to the second host node; The determining, based on the first information, that the terminal device needs to perform a random access-free switching process includes: receiving a cell identifier of the source cell and a cell identifier of the target cell from the second host node; In response to the cell identifier of the source cell being in the cell information of the first cell and the cell identifier of the target cell being in the cell information of the second cell, determining that the source cell and the target cell are cells of the relay node; the second cell is a cell activated when the relay node is connected to the first host node; In response to the source cell and the target cell being cells of the relay node, it is determined that the terminal device needs to perform the random access-free switching process.

13. The method according to any one of claims 1 to 12, characterized in that: The method is applied to a first host node; the relay node has established a connection with the first host node; or, the connection between the relay node and the host node is migrated from a second host node to the first host node.

14. The method according to any one of claims 1 to 3, characterized in that: The method is applied to a second host node, and the connection between the relay node and the host node is migrated from the second host node to the first host node.

15. The method according to claim 14, characterized in that The sending the random access-free switching configuration information to the terminal device includes: Sending the first beam information to the first host node; receiving the random access-free switching configuration information from the first host node; The random access-free switching configuration information is sent to the terminal device via a source DU; the source DU belongs to the relay node.

16. The method according to claim 14 or 15, characterized in that The method further comprises: Send beam measurement information of the target cell to the first host node.

17. The method according to any one of claims 14 to 16, characterized in that: The method further comprises: Sending first information to the first host node; The first information is used to indicate that the source cell of the terminal device and the target cell of the terminal device are cells of the relay node; or the first information indicates that the terminal device needs to perform the random access-free switching process.

18. The method according to claim 17, characterized in that The method further comprises: Sending a cell identifier of the source cell and a cell identifier of the target cell to the first donor node.

19. A communication method, characterized in that: The method comprises: Receiving beam measurement information of a target cell of a terminal device from a first host node, the beam measurement information including a beam identifier of at least one beam; Determine, based on the beam measurement information of the target cell, first beam information to be used by the terminal device to communicate with the target cell, where the first beam information includes a beam identifier of the first beam; and the at least one beam includes the first beam; The first beam information is sent to the first host node.

20. A communication method, characterized in that: The method comprises: Receiving first beam information from a first host node, where the first beam information includes a beam identifier of the first beam, and the first beam information is beam information to be used by the terminal device to communicate with the target cell; The first beam information is sent to the first host node, where the first beam information is included in an RRC message.

21. The method according to claim 19 or 20, characterized in that The method further comprises: Sending first information to the first host node, where the first information indicates cell information of a first cell, where the first cell is a cell activated when the relay node is connected to the second host node.

22. The method according to any one of claims 19 to 21, characterized in that: The method is applied to a target DU, the target DU belongs to a relay node, and the source cell of the terminal device and the target cell are cells of the relay node.

23. A communication device, characterized in that: The communication device includes a processing module and a transceiver module; the processing module and the transceiver module are used for the communication device to implement the method described in any one of claims 1-18, or to implement the method described in any one of claims 19-22.

24. A communication device, characterized in that: The communication device comprises: a processor, the processor is coupled to a memory, the memory is used to store programs or instructions, when the program or instructions are executed by the processor, the communication device executes the method as described in any one of claims 1-18, or the method as described in any one of claims 19-22.

25. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instructions are executed, the computer performs the method according to any one of claims 1 to 18, or the method according to any one of claims 19 to 22.

26. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instructions are executed, the computer performs the method according to any one of claims 1 to 18, or the method according to any one of claims 19 to 22.

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