Method of cell handover and apparatus using same
By coordinating the operation of network nodes and user equipment, the problem of limited LTM application scope within a centralized unit was solved, enabling cell handover across CUs and reducing mobility latency.
Patent Information
- Application Number
- CN202510596669.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-05-10
- Filing Date
- 2025-05-09
- Publication Date
- 2025-11-11
AI Technical Summary
LTM within a centralized cell only supports cell movement within the same generation node B or the same CU, limiting its application scope and making it impossible to achieve cell handover across CUs.
Through coordinated operation of network nodes and user equipment, cell handover requests are initiated and confirmed, candidate cell information is updated, and cell handover is performed across CUs or within CUs. Cell handover is carried out using cross-CU LTM configuration or intra-CU LTM configuration.
It enables efficient cell handover between centralized units, reduces mobility latency, and expands the application scope of cell handover.
Smart Images
Figure CN120935679A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a cell handover method, a network node, and user equipment (UE). Background Technology
[0002] L1 / L2 triggered mobility (LTM) within an intra-centralized unit (intra-CU) offers lower mobility latency compared to traditional L3-based mobility mechanisms. However, intra-CU LTM only supports cell mobility within the same Next Generation Node B (gNB) or the same CU, thus significantly limiting its application scope. Summary of the Invention
[0003] This disclosure provides a method for cell handover, as well as a network node and UE using the same method. This disclosure can manage cell handover mobility between the same CU or between different CUs.
[0004] This disclosure provides a method for cell handover performed by a first network node. The method includes initiating a request message to request cell handover-related configurations for at least one candidate cell, wherein the at least one candidate cell belongs to a second network node. Receiving a request confirmation message from the second network node, wherein the request confirmation message contains a first configuration for at least one accepted candidate cell. Transmitting a first message to the second network node to update information about the at least one accepted candidate cell. Transmitting a second configuration to a user equipment.
[0005] This disclosure provides a method for cell handover performed by a user equipment. The method includes receiving configurations of at least one candidate cell from a first network node; receiving a cell handover command from the first network node; performing a cell handover to a target cell according to the cell handover command; transmitting a completion message to the target cell to complete the cell handover; and receiving a message from the target cell in response to the completion message, wherein the message includes at least one of the following: updated information of at least one candidate cell, updated measurement configuration, or an updated list of central cell identifiers.
[0006] This disclosure provides a first network node. The first network node includes a transceiver and a processor coupled to the transceiver. The processor is configured to: initiate a request message via the transceiver to request cell handover-related configurations for at least one candidate cell, wherein the at least one candidate cell belongs to a second network node; receive a request confirmation message via the transceiver from the second network node, wherein the request confirmation message includes a first configuration for at least one accepted candidate cell; transmit a first message via the transceiver to the second network node to update information about the at least one accepted candidate cell; and transmit a second configuration via the transceiver to a user equipment.
[0007] This disclosure provides a user equipment. The user equipment includes a transceiver and a processor coupled to the transceiver. The processor is configured to: receive configurations of at least one candidate cell from a first network node via the transceiver; receive a cell handover command from the first network node via the transceiver; perform a cell handover to a target cell according to the cell handover command; transmit a completion message to the target cell via the transceiver to complete the cell handover; and, in response to transmitting the completion message to the target cell, receive a message from the target cell via the transceiver, wherein the message includes at least one of the following: information of at least one updated candidate cell, an updated measurement configuration, or an updated list of central cell identifiers.
[0008] To make the foregoing more understandable, several embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description
[0009] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in this specification. These drawings illustrate exemplary embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure.
[0010] Figure 1 This document describes a cell handover signaling diagram according to an embodiment of the present disclosure.
[0011] Figure 2 This illustration shows an information transmission signaling diagram during the preparation phase according to an embodiment of the present disclosure.
[0012] Figure 3 This describes an information transmission signaling diagram after a target cell has been selected according to an embodiment of the present disclosure.
[0013] Figure 4 This describes a signaling diagram illustrating information transmission after a target cell has been selected, according to another embodiment of this disclosure.
[0014] Figure 5 A flowchart illustrating a cell handover method according to an embodiment of the present disclosure is provided.
[0015] Figure 6 A flowchart illustrating a cell handover method according to an embodiment of the present disclosure is provided.
[0016] Figure 7 A schematic diagram of a communication device according to an embodiment of the present disclosure is shown. Detailed Implementation
[0017] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.
[0018] Based on the Rel 18 LTM procedure, cell handover is triggered by an LTM cell switch command (CSC) sent by the current serving node. The cell switch command indicates which candidate cell is available for handover. The serving gNB can delegate the task of triggering the cell handover to the UE via information transmission. Figure 1 This document describes a cell handover signaling diagram according to an embodiment of the present disclosure.
[0019] In step S101, the current serving node (e.g., a network node, serving cell, serving gNB, or serving CU) may initiate a request message to request cell handover-related configurations for each of one or more candidate cells. Specifically, the current serving node may transmit a cell handover request to one or more candidate nodes, where one or more candidate nodes (e.g., candidate network node, candidate cell, candidate gNB, or candidate CU) may include a target node. The cell handover request may be associated with cross-CU LTM configurations or intra-CU LTM configurations. That is, the preparation of cross-CU LTM configurations or intra-CU LTM configurations may be initiated by the serving node. The cell handover request may instruct one of the one or more candidate nodes to prepare configurations for its N candidate cells, where N is a positive integer.
[0020] In one embodiment, the serving node and the candidate node may be served by the same base station (BS) (e.g., the same CU). In another embodiment, the serving node and the candidate node may be served by different base stations (e.g., different CUs).
[0021] In step S102, a candidate node (e.g., the target node or other candidate nodes) may transmit a cell handover request acknowledgment (ACK) to the serving node. The serving cell is responsible for collecting the configuration and information of candidate cells from multiple cell handover request ACKs, which may be transmitted from multiple candidate nodes respectively. In one embodiment, the cell handover request ACK may contain the configuration of M accepted candidate cells, where M is a positive integer and M≤N. The M accepted candidate cells may be a subset of the N candidate cells. That is, the candidate node may determine whether to prepare all or part of the information of the candidate cells requested by the serving node, wherein the requested candidate cells may belong to the candidate node.
[0022] In step S103, the serving node may transmit a pre-configuration to the UE to perform a cell handover to the target cell. In one embodiment, the pre-configuration may be associated with a cross-CU LTM configuration or an intra-CU LTM configuration.
[0023] In step S104, the serving node may transmit a cell handover command associated with the target cell to the UE. The UE may then perform a cell handover from the serving cell (e.g., a cell belonging to the serving node) to the target cell (e.g., a cell belonging to the target node) according to the cell handover command. Specifically, the UE may apply cross-CU LTM configuration or intra-CU LTM configuration to perform the cell handover.
[0024] In step S105, the UE can notify the target node that it is fully ready to perform cell handover by transmitting a configuration completion message to the target node. After the target node receives the configuration completion message, the UE and the target node can perform cell handover from the serving cell to the target cell.
[0025] The target cell and the UE can determine whether the cell handover has been completed. If the cell handover has been completed, in step S106, the target node can transmit a cell handover completion message (or success message) to the serving node. The cell handover completion message indicates that the UE has successfully accessed the target node's target cell.
[0026] The serving node can provide the UE with information via pre-configuration messages regarding which LTM configuration (cross-CU LTM configuration or intra-CU LTM configuration) can be applied to perform cell handover. The UE can then decide whether to apply the cross-CU LTM configuration or the intra-CU LTM configuration to perform cell handover based on the pre-configuration message. Some operations can be inserted into... Figure 1 The signaling diagram shown illustrates the information transmission method for cell handover.
[0027] Figure 2This describes an information transmission signaling diagram during the preparation phase according to an embodiment of this disclosure. To support LTM (Live Telemetry and Metering), the serving node (e.g., the source gNB-CU) needs to notify candidate nodes (e.g., candidate gNB-CUs) about common channel state information (CSI) resource configuration or information collected from one or more candidate nodes (e.g., candidate gNB-CUs). Specifically, after receiving a cell handover request ACK from a candidate node (e.g., the target node or other candidate nodes), in step S201, the serving node may transmit a first message to the candidate node. The first message may be transmitted before the cell handover command or pre-configuration transmission. The first message can be used to update information about candidate cells. The first message may include a list of candidate cells, one or more candidate cell measurement configurations, or a list of CU identifiers (IDs). The content of the first message can be used by the target node after the UE performs a cell handover from the serving cell to the target cell.
[0028] In one embodiment, the service node can communicate with the candidate node via the Xn interface.
[0029] The candidate cell list can indicate one or more accepted candidate cells for UE handover. For example, the candidate cell list can record the IDs of one or more accepted candidate cells. The candidate cell measurement configuration can include a common CSI resource configuration. The CU ID list can include the CU ID (or group identifier, group ID) of the serving cell and the CU IDs (or group IDs) of one or more accepted candidate cells. The CU ID of the serving cell and the CU IDs of the accepted candidate cells can be the same or different.
[0030] Optionally, in step S202, a candidate node (e.g., a target node or other candidate node) may transmit a second message to the serving node in response to the first message. The second message may include an updated candidate cell list, one or more updated candidate cell measurement configurations, or an updated CUID list. The updated candidate cell list may indicate one or more updated accepted candidate cells for UE handover. The updated candidate cell measurement configuration may include an updated common CSI resource configuration. The updated CUID list may include updated CUIDs of the serving cell and updated CUIDs of one or more updated accepted candidate cells.
[0031] For example, after receiving the candidate cell list from the serving node, the candidate node can determine whether the candidate cell list needs to be updated. If the candidate cell list needs to be updated, the candidate node can update the candidate cell list and transmit the updated candidate cell list to the serving node via a second message.
[0032] In step S103, the pre-configuration message transmitted from the serving node to the UE can be associated with the second message. For example, the pre-configuration message may include the CU ID of the serving cell and the CU ID of the target cell. If the CU ID of the serving cell is the same as the CU ID of the target cell, the UE can determine that the serving cell and the target cell are served by the same CU. Therefore, the UE can apply the intra-CU LTM configuration to perform a cell handover from the serving cell to the target cell. If the CU ID of the serving cell is different from the CU ID of the target cell, the UE can determine that the serving cell and the target cell are served by different CUs. Therefore, the UE can apply the cross-CU LTM configuration to perform a cell handover from the serving cell to the target cell.
[0033] In one embodiment, the serving node may select a target cell from multiple candidate cells. The serving node may determine whether to hand over the UE to the target cell. After determining to hand over the UE to the target cell, the serving node may transmit a first message to the target node.
[0034] Figure 3 This describes a signaling diagram for information transmission after a target cell is selected, according to an embodiment of this disclosure. After the target cell is selected, in step S301-1, the serving node may transmit a first message to the target node in response to a cell handover command transmitted from the serving node to the UE. The first message may include a candidate cell list, one or more candidate cell measurement configurations, or a CUID list.
[0035] Optionally, after the cell handover from the serving node to the target node is completed, in step S302, the target node may transmit a second message to the UE. The second message may include an updated candidate cell list, one or more updated candidate cell measurement configurations, or an updated CUID list.
[0036] In one embodiment, Figure 3 The method shown can be used as Figure 2 Alternative plans for the method shown. For example, the service node may attempt to transmit a first message to one or more candidate nodes in step S201. If the service node fails to transmit the first message to the target node in step S201 (the failed first message may also be referred to as the third message), the service node may transmit the first message to the target node again in step S301-1.
[0037] Figure 4This describes the information transmission signaling diagram after a target cell is selected according to another embodiment of this disclosure. After the target cell is selected, if the cell handover performed by the UE is successful, the target node can transmit a cell handover completion message (or success message) to the serving cell. The cell handover completion message indicates that the UE has successfully accessed the target cell of the target node. If the cell handover is successful, in step S301-2, the serving node can transmit a first message to the target node. The first message may include a candidate cell list, one or more candidate cell measurement configurations, or a CUID list.
[0038] After the cell handover from the serving node to the target node is completed, in step S302, the target node may transmit a second message to the UE. This second message may include an updated candidate cell list, one or more updated candidate cell measurement configurations, or an updated CUID list.
[0039] In one embodiment, Figure 4 The method shown can be used as Figure 2 or Figure 3 Alternative plans for the method shown. For example, the service node may attempt to transmit the first message to one or more candidate nodes in step S201, or may attempt to transmit the first message to the target node in step S301-1. If the service node fails to transmit the first message to the candidate node or the target node in step S201 or step S301-1, the service node may transmit the first message to the target node again in step S301-2.
[0040] Figure 5 This document describes a flowchart of a cell handover method according to an embodiment of the present disclosure, wherein the method is performed by a network node. In step S501, a request message is initiated to request cell handover-related configurations for at least one candidate cell, wherein the at least one candidate cell belongs to a second network node. In step S502, a request confirmation message is received from the second network node, wherein the request confirmation message contains a first configuration for at least one accepted candidate cell. In step S503, a first message is transmitted to the second network node to update information about the at least one accepted candidate cell. In step S504, a second configuration is transmitted to the user equipment.
[0041] Figure 6This document describes a flowchart of a cell handover method according to an embodiment of the present disclosure, wherein the method is performed by a UE. In step S601, configurations of at least one candidate cell are received from a first network node. In step S602, a cell handover command is received from the first network node. In step S603, a cell handover to a target cell is performed according to the cell handover command. In step S604, a completion message is transmitted to the target cell to complete the cell handover. In step S605, in response to the completion message being transmitted to the target cell, a message is received from the target cell, wherein the message contains at least one of the following: information of at least one updated candidate cell, an updated measurement configuration, or an updated list of central cell identifiers.
[0042] Figure 7 The illustration shows a communication device 100 according to an embodiment of the present disclosure, wherein the communication device 100 may be implemented as the UE or network node described above. The communication device 100 may include a processor 110, a storage medium 120, and a transceiver 130. The processor 110 is coupled to the storage medium 120 and the transceiver 130. The processor 110 may be configured to at least implement... Figure 1-6 The methods described herein, along with their exemplary embodiments and alternative variations.
[0043] Processor 110 can be implemented using programmable units, such as microprocessors, microcontrollers, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), etc. The functions of processor 110 can also be implemented using separate electronic devices or ICs. It should be noted that the functions of processor 110 can be implemented in hardware or software.
[0044] Storage medium 120 may be, for example, any type of fixed or removable random access memory (RAM), read-only memory (ROM), flash memory, hard disc drive (HDD), solid state drive (SSD), or similar element, or a combination thereof, configured to record multiple modules or various applications that can be executed by processor 110.
[0045] Transceiver 130 can be configured to transmit and receive signals in radio frequency. Transceiver 130 can also perform operations such as low-noise amplification, impedance matching, frequency mixing, up- or down-frequency conversion, filtering, and amplification. Transceiver 130 may include one or more digital-to-analog (D / A) converters or analog-to-digital (A / D) converters configured to convert from analog signal format to digital signal format during uplink signal processing and from digital signal format to analog signal format during downlink signal processing. Transceiver 130 may include an antenna array containing one or more antennas for transmitting and receiving omnidirectional or directional antenna beams.
[0046] Based on the above, cell handover information between the same or different CUs (sequential) can be transmitted or received between the UE, the serving node, and one or more (candidate) target nodes. This information can be transmitted or received during the preparation phase or after the target cell (and its corresponding target node) has been selected. If the transmission or reception of information fails at an earlier stage, a backup plan can be applied. For example, if the transmission or reception of information fails during the preparation phase, the target node can transmit the information required by the UE to the UE after the target node is selected. The UE can then perform cross-CU cell handover or intra-CU cell handover based on the received information.
[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 invention.
Claims
1. A method for cell handover, executed by a first network node, characterized in that, include: Initiate a request message to request cell handover-related configurations for at least one candidate cell, wherein the at least one candidate cell belongs to the second network node; Receive a request confirmation message from the second network node, wherein the request confirmation message includes a first configuration of at least one accepted candidate cell; Transmit a first message to the second network node to update the information of the at least one accepted candidate cell; as well as Transmit the second configuration to the user equipment.
2. The method of claim 1, wherein the first message includes at least one of the following: the information of the at least one accepted candidate cell, a measurement configuration or a list of centralized unit identification codes, wherein the list of centralized unit identification codes includes a first group identification code of the serving cell and at least one second group identification code of the at least one accepted candidate cell.
3. The method according to claim 1, further comprising: In response to transmitting the first message, a second message is received from the second network node.
4. The method of claim 3, wherein the second message includes at least one of the following: information on at least one updated accepted candidate cell, an updated measurement configuration, or an updated list of central cell identifiers.
5. The method of claim 3, wherein the second configuration includes information associated with the second message.
6. The method of claim 1, wherein the first message is transmitted before the second configuration is transmitted to the user equipment.
7. The method according to claim 1, wherein a cell handover command associated with the second network node is transmitted to the user equipment.
8. The method of claim 7, further comprising: Receive a success message from the second network node, wherein the success message indicates that the user equipment has successfully accessed the second network node.
9. The method of claim 8, wherein the first message is transmitted to the second network node in response to the receipt of the success message.
10. The method of claim 9, wherein the step of transmitting the first message to the second network node comprises: In response to the transmission of the cell handover command, the transmission of the third message is performed to the second network node; as well as In response to the transmission failure, the first message is transmitted to the second network node in response to receiving the success message.
11. The method of claim 10, wherein the third message includes at least one of the following: the information of the at least one accepted candidate cell, a measurement configuration, or a list of central cell identifiers.
12. The method of claim 7, wherein the first message is transmitted to the second network node in response to the cell handover command being transmitted.
13. The method of claim 1, wherein the first message is transmitted from the first network node to the second network node via the Xn interface.
14. A method for cell handover, performed by a user equipment, characterized in that, include: Receive configurations for at least one candidate cell from the first network node; Receive cell handover command from the first network node; The cell handover command is executed to perform a cell handover to the target cell; A completion message is transmitted to the target cell to complete the cell handover. as well as In response to transmitting the completion message to the target cell, a message is received from the target cell, wherein the message includes at least one of the following: information on at least one updated candidate cell, an updated measurement configuration, or an updated list of central cell identifiers.
15. A first network node, characterized in that, include: transceiver; as well as A processor, coupled to the transceiver, wherein the processor is configured to: The transceiver initiates a request message to request cell handover-related configurations for at least one candidate cell, wherein the at least one candidate cell belongs to the second network node. The transceiver receives a request confirmation message from the second network node, wherein the request confirmation message includes a first configuration of at least one accepted candidate cell; The transceiver transmits a first message to the second network node to update the information of the at least one accepted candidate cell; as well as The second configuration is transmitted to the user equipment via the transceiver.
16. A user equipment, characterized in that, include: transceiver; as well as A processor, coupled to the transceiver, wherein the processor is configured to: The transceiver receives the configuration of at least one candidate cell from the first network node. The transceiver receives a cell handover command from the first network node. The cell handover command is executed to perform a cell handover to the target cell; The transceiver transmits a completion message to the target cell to complete the cell handover. as well as In response to transmitting the completion message to the target cell, a message is received from the target cell via the transceiver, wherein the message includes at least one of the following: information on at least one updated candidate cell, an updated measurement configuration, or an updated list of central cell identifiers.