WO2024255719A1 - 一种切换方法和通信装置 - Google Patents

一种切换方法和通信装置 Download PDF

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Publication number
WO2024255719A1
WO2024255719A1 PCT/CN2024/098315 CN2024098315W WO2024255719A1 WO 2024255719 A1 WO2024255719 A1 WO 2024255719A1 CN 2024098315 W CN2024098315 W CN 2024098315W WO 2024255719 A1 WO2024255719 A1 WO 2024255719A1
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WIPO (PCT)
Prior art keywords
target
source
information
terminal device
notification message
Prior art date
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Ceased
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PCT/CN2024/098315
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English (en)
French (fr)
Inventor
顾志方
酉春华
范强
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Priority to EP24822669.8A priority Critical patent/EP4723733A1/en
Publication of WO2024255719A1 publication Critical patent/WO2024255719A1/zh
Priority to US19/417,481 priority patent/US20260113676A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • H04W36/087—Reselecting an access point between radio units of access points

Definitions

  • the present application relates to the field of communication technology, and more specifically, to a switching method and a communication device.
  • the movement of a terminal device may cause a change in the communication link between the terminal device and a network device.
  • the network device may instruct the terminal device to perform a cell switch according to the movement of the terminal device.
  • the present application provides a switching method and a communication device, which can reduce the data that undergoes data forwarding, thereby reducing invalid data and further improving the service experience.
  • a switching method is provided, which can be executed by a source centralized unit (CU) or by a module or unit (such as a chip or circuit) in the source CU.
  • the source CU is used for description below.
  • the method includes: a source CU receives a first notification message from a source distributed unit (DU), wherein the first notification message is used to indicate a target cell to which a terminal device will switch, and the target cell is a cell of a target DU under a target CU; the source CU sends a first request message to a core network device according to the first notification message, wherein the first request message is used to request that the user plane bearer of the terminal device be switched to the target CU.
  • DU source distributed unit
  • the source CU can initiate the switching of the user plane bearer of the terminal device according to the first notification message used to indicate the target cell to which the terminal device will switch.
  • the switching of the user plane bearer of the terminal device can be triggered by the first notification message.
  • the above method can execute the switching of the user plane bearer of the terminal device earlier. After executing the switching of the user plane bearer of the terminal device, the service data of the terminal device can be sent directly to the target CU without going through the data forwarding process from the source CU to the target CU. Therefore, the above method can reduce the data forwarded from the source CU to the target CU, thereby reducing invalid data and improving the service experience.
  • the first notification message includes the first identifier of the target cell; the source CU sends a first request message to the core network device based on the first notification message, including: the source CU sends the first request message to the core network device based on the first identifier and a first association relationship, the first association relationship is used to indicate the association relationship between the first identifier and the first information, the first information is used to indicate the channel information carried by the user plane of the target CU, and the first request message includes the first information.
  • the source CU can obtain the channel information of the user plane bearer of the target CU according to the first identifier of the target cell and the first association relationship between the channel information used to indicate the user plane bearer of the target CU, thereby providing the channel information of the user plane bearer of the target CU to the core network device, thereby realizing the switching of the user plane bearer of the terminal device initiated by the source CU.
  • the method before the source CU receives the first notification message, the method also includes: the source CU sends a second request message to the target CU, the second request message is used to request the first information; the source CU receives a second response message from the target CU, the second response message includes a second identifier of the target cell and the first information; the source CU determines the first association relationship based on the second identifier and the first information.
  • the first notification message includes the target small The first identifier of the zone; the source CU sends a first request message to the core network device according to the first notification message, including: the source CU determines the identifier of the target CU to which the target cell belongs according to the first identifier; the source CU sends the first request message to the core network device according to the identifier of the target CU and a second association relationship, the second association relationship is used to indicate the association relationship between the identifier of the target CU and the first information, the first information is used to indicate the channel information carried by the user plane of the target CU, and the first request message includes the first information.
  • the source CU can obtain the channel information of the user plane bearer of the target CU according to the first identifier of the target cell, the target CU and the second association relationship between the channel information of the user plane bearer indicating the target CU, thereby providing the channel information of the user plane bearer of the target CU to the core network device, thereby realizing the switching of the user plane bearer of the terminal device initiated by the source CU.
  • the method before the source CU sends a first request message to the core network device based on the first notification message, the method also includes: the source CU sends a second request message to the target CU, the second request message is used to request the first information; the source CU receives a second response message from the target CU, the second response message includes an identifier of the target CU and the first information; the source CU determines the second association relationship based on the identifier of the target CU and the first information.
  • the second request message also includes second information, and the second information is used to request that the source CU initiate a path switch; the second response message also includes third information, and the third information is used to indicate that the source CU is allowed to initiate a path switch.
  • the source CU and the target CU can negotiate to determine that the source CU initiates the switching of the user plane bearer of the terminal device, which helps to initiate the switching of the user plane bearer of the terminal device by a more suitable CU.
  • the second request message further includes fourth information, where the fourth information is used to indicate that the path switching is initiated by the source CU.
  • the source CU determines to initiate the switching of the user plane bearer of the terminal device, it only needs to notify the target CU without the confirmation or permission of the target CU.
  • the method further includes: the source CU sends at least one association relationship to a candidate CU, the candidate CU includes the target CU, and the at least one association relationship includes the first association relationship.
  • the target CU serves as the source CU for subsequent switching, it is not necessary to re-obtain the association relationship between the candidate cell and the channel information carried by the user plane of the corresponding candidate CU, thereby reducing the signaling overhead and allowing the subsequent switching process and the corresponding path switching process to be executed faster.
  • the first information includes at least one of the following information: an Internet Protocol (IP) address of a downlink endpoint of a user plane bearer of the target CU, or a GPRS tunneling protocol-tunnel endpoint identifier (GTP-TEID) of a downlink endpoint of a user plane bearer of the target CU.
  • IP Internet Protocol
  • GTP-TEID GPRS tunneling protocol-tunnel endpoint identifier
  • the method further includes: the source CU forwarding the service data of the terminal device to the target CU according to the first notification message.
  • the method further includes: the source CU sends a second notification message to the target CU, and the second notification message is used to indicate the target cell to which the terminal device will switch.
  • the second notification message includes at least one of the following information: a first identifier of the target cell, beam information, or access information, wherein the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal device, and the access information is used to indicate the access method used by the terminal device to access the target cell.
  • the method also includes: the source CU sends the correspondence between the first identifier of the target cell and the second identifier of the target cell to the target CU, the first identifier being the identifier of the target cell on the air interface, and the second identifier being the identifier of the target cell on the network side.
  • the above method can enable the target CU to know the corresponding relationship between the first identifier of the target cell and the second identifier of the target cell.
  • the source CU and the target CU communicate with the terminal, they can use the same first identifier of the candidate cell, which can avoid repeated configuration of the terminal device.
  • the length of the first identifier is smaller than the length of the second identifier. In this way, the signaling overhead of the air interface can be reduced.
  • the method further includes: the source CU receiving a first response message from the core network device, the first response message being used to indicate that the path switching is successful.
  • the method further includes: the source CU receives a fifth notification message from the target CU, and the fifth notification message is used to indicate that the terminal device has successfully accessed the target cell.
  • a switching method is provided.
  • the method can be executed by a target CU or by a module or unit (such as a chip or circuit) in the target CU.
  • the target CU is used for description below.
  • the method includes: the target CU receives a second request message from the source CU, the second request message is used to request first information, and the first information is used to indicate the channel information carried by the user plane of the target CU; the target CU sends a second response message to the source CU, the second response message includes a second identifier of a target cell and the first information, and the target cell is a cell of a target distributed unit DU under the target CU.
  • the second request message also includes second information, and the second information is used to request that the source CU initiate a path switch; the second response message also includes third information, and the third information is used to indicate that the source CU is allowed to initiate a path switch.
  • the second request message further includes fourth information, where the fourth information is used to indicate that the path switching is initiated by the source CU.
  • the method also includes: the target CU receives at least one association relationship from the source CU, and the at least one association relationship includes a first association relationship, and the first association relationship is used to indicate the association relationship between the first identifier of the target cell and the first information.
  • the method also includes: the target CU receives the service data of the terminal device from the source CU; the target CU sends the service data to the target DU; after sending the service data to the target DU, the target CU receives a fourth notification message from the target DU, and the fourth notification message is used to indicate that the terminal device has successfully accessed the target cell.
  • the target DU can immediately send data to the terminal device, which is conducive to sending the data to the terminal device as soon as possible and avoiding data failure.
  • the method further includes: the target CU sends a fifth notification message to the source CU, and the fifth notification message is used to indicate that the terminal device has successfully accessed the target cell.
  • the method further includes: the target CU receives a second notification message from the source CU, and the second notification message is used to indicate the target cell to which the terminal device will switch.
  • the second notification message includes at least one of the following information: a first identifier of the target cell, beam information, or access information, wherein the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal device, and the access information is used to indicate the access method used by the terminal device to access the target cell.
  • the method also includes: the target CU sends a sixth notification message to the target DU based on the second notification message, and the sixth notification message includes at least one of the following information: the first identifier of the target cell, the beam information, or the access information.
  • the second notification message includes seventh information, and the seventh information is used to indicate that the source CU has initiated a path switch; the method also includes: the target CU does not perform a path switch based on the seventh information.
  • the method also includes: the target CU receives the correspondence between the first identifier of the target cell and the second identifier of the target cell from the source CU, the first identifier being the identifier of the target cell on the air interface, and the second identifier being the identifier of the target cell on the network side.
  • a switching method is provided, which can be executed by a target CU or by a module or unit in the target CU. (such as a chip or circuit) for execution, and the target CU is used for description below.
  • the method includes: the target CU receives a first notification message from the source CU, the first notification message is used to indicate the target cell to which the terminal device will switch, and the target cell is the cell of the target DU under the target CU; the target CU sends a first request message to the core network device based on the first notification message, and the first request message is used to request to switch the user plane bearer of the terminal device to the target CU.
  • the target CU can initiate the switching of the user plane bearer of the terminal device according to the first notification message used to indicate the target cell to which the terminal device will switch.
  • the switching of the user plane bearer of the terminal device can be triggered by the first notification message.
  • the above method can execute the switching of the user plane bearer of the terminal device earlier. After executing the switching of the user plane bearer of the terminal device, the service data of the terminal device can be sent directly to the target CU without going through the data forwarding process from the source CU to the target CU. Therefore, the above method can reduce the data forwarded from the source CU to the target CU, thereby reducing invalid data and improving the service experience.
  • the first notification message includes fifth information, and the fifth information is used to indicate that the source CU does not initiate a path switch.
  • the method before receiving the first notification message from the source CU, the method also includes: the target CU receives a second request message from the source CU, the second request message is used to request first information, the first information is used to indicate the channel information carried by the user plane of the target CU, the second request message also includes second information, and the second information is used to request that the source CU initiate a path switch; the target CU sends a second response message to the source CU, the second response message includes sixth information, and the sixth information is used to indicate that the source CU is not allowed to initiate a path switch.
  • the source CU and the target CU can negotiate to determine that the source CU initiates the switching of the user plane bearer of the terminal device, which helps to initiate the switching of the user plane bearer of the terminal device by a more suitable CU.
  • the first information includes at least one of the following information: the IP address of the downlink endpoint carried by the user plane corresponding to the target CU, or the GTP-TEID of the downlink endpoint carried by the user plane corresponding to the target CU.
  • the first notification message includes at least one of the following information: a first identifier of the target cell, beam information, or access information, wherein the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal device, and the access information is used to indicate the access method used by the terminal device to access the target cell.
  • the method also includes: the target CU sends a third notification message to the target DU based on the first notification message, and the third notification message includes at least one of the following information: the first identifier, the beam information, or the access information.
  • the method further includes: the target CU receives at least one association relationship from the source CU, and the association relationship is used to indicate the association relationship between the identifier of the candidate cell and the channel information carried by the user plane of the candidate CU corresponding to the candidate cell.
  • the target CU serves as the source CU for subsequent switching, it is not necessary to re-obtain the association relationship between the candidate cell and the channel information carried by the user plane of the corresponding candidate CU, thereby reducing the signaling overhead and allowing the subsequent switching process and the corresponding path switching process to be executed faster.
  • the method also includes: the target CU receives the service data of the terminal device from the source CU; the target CU sends the service data to the target DU; after sending the service data to the target DU, the target CU receives a fourth notification message from the target DU, and the fourth notification message is used to indicate that the terminal device has successfully accessed the target cell.
  • the target DU can immediately send data to the terminal device, which is conducive to sending the data to the terminal device as soon as possible and avoiding data failure.
  • the method also includes: the target CU receives the correspondence between the first identifier of the target cell and the second identifier of the target cell from the source CU, the first identifier being the identifier of the target cell on the air interface, and the second identifier being the identifier of the target cell on the network side.
  • the above method can enable the target CU to know the corresponding relationship between the first identifier of the target cell and the second identifier of the target cell.
  • the source CU and the target CU communicate with the terminal, they can use the same first identifier of the candidate cell, which can avoid repeated configuration of the terminal device.
  • the length of the first identifier is smaller than the length of the second identifier. In this way, the signaling overhead of the air interface can be reduced.
  • the method further includes: the target CU receives a first response message from a core network device, where the first response message is used to indicate that the path switching is successful.
  • a switching method is provided.
  • the method can be executed by a source CU or by a module or unit (such as a chip or circuit) in the source CU.
  • the source CU is used for description below.
  • the method includes: the source CU receives an eighth notification message from the source DU, the eighth notification message is used to indicate the target cell to which the terminal device will switch, and the target cell is the cell of the target DU under the target CU; the source CU sends a first notification message to the target CU based on the eighth notification message, and the first notification message is used to indicate the target cell to which the terminal device will switch.
  • the first notification message includes fifth information, and the fifth information is used to indicate that the source CU does not initiate a path switch.
  • the method before the source CU sends a first notification message to the target CU according to the eighth notification message, the method also includes: the source CU sends a second request message to the target CU, the second request message is used to request first information, the first information is used to indicate the channel information carried by the user plane of the target CU, the second request message also includes second information, and the second information is used to request that the source CU initiate a path switch; the source CU receives a second response message from the target CU, the second response message includes sixth information, and the sixth information is used to indicate that the source CU is not allowed to initiate a path switch.
  • the first notification message also includes at least one of the following information: a first identifier of the target cell, beam information, or access information, wherein the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal, and the access information is used to indicate the access method used by the terminal device to access the target cell.
  • the method further includes: the source CU sends at least one association relationship to the candidate CU, the candidate CU includes the target CU, and the association relationship is used to indicate the association relationship between the identifier of the candidate cell and the channel information carried by the user plane of the candidate CU corresponding to the candidate cell.
  • the method further includes: the source CU forwarding the service data of the terminal device to the target CU according to the eighth notification message.
  • the method also includes: the source CU sends the correspondence between the first identifier of the target cell and the second identifier of the target cell to the target CU, the first identifier being the identifier of the target cell on the air interface, and the second identifier being the identifier of the target cell on the network side.
  • a switching method is provided.
  • the method can be executed by a target access network device or by a module or unit (such as a chip or circuit) in the target access network device.
  • the target access network device is used for description below.
  • the method includes: a target access network device determines configuration information of a target cell, the configuration information of the target cell includes configuration information of a first carrier, the first carrier is a normal uplink (NUL) carrier or a supplementary uplink (SUL) carrier; the target access network device sends the configuration information of the target cell to a terminal device.
  • NUL normal uplink
  • SUL supplementary uplink
  • the target access network device sends the configuration information of the target cell to the terminal device through the source access network device.
  • the target access network device can determine whether to use NUL or SUL to complete the switching process of the target cell, and provide the terminal device with the configuration information of the corresponding carrier, so that the terminal device can use the configuration information of the carrier to switch to the target cell, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a terminal device or by a module or unit (such as a chip or circuit) in the terminal device.
  • the terminal device is used for description below.
  • the method includes: a terminal device receives configuration information of a target cell from a target access network device, the configuration information of the target cell includes configuration information of a first carrier, and the first carrier is a NUL carrier or a SUL carrier; the terminal device receives a switching command from a source access network device, and the switching command is used to indicate switching to the target cell; the terminal device uses the first carrier to perform a switching process to the target cell according to the configuration information of the target cell.
  • the target access network device can determine whether to use NUL or SUL to complete the switching process of the target cell, and provide the terminal device with the configuration information of the corresponding carrier.
  • the terminal device can use the configuration information of the carrier to switch to the target cell, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a target access network device or by a module or unit (such as a chip or circuit) in the target access network device.
  • the target access network device is used for description below.
  • the method includes: a target access network device determines configuration information of a target cell, the configuration information of the target cell includes configuration information of a NUL carrier, configuration information of a SUL carrier, and carrier information, the carrier information is used to indicate that the switching process of the target cell is completed using the NUL carrier, or the carrier information is used to indicate that the switching process of the target cell is completed using the SUL carrier; the target access network device sends the configuration information of the target cell to a terminal device.
  • the target access network device can determine whether to use NUL or SUL to complete the switching process for the target cell and indicate it to the terminal device, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a terminal device or by a module or unit (such as a chip or circuit) in the terminal device.
  • the terminal device is used for description below.
  • the method includes: a terminal device receives configuration information of a target cell from a target access network device, the configuration information of the target cell includes configuration information of a NUL carrier, configuration information of a SUL carrier, and carrier information, the carrier information is used to indicate the use of a first carrier to complete a switching process of the target cell, the first carrier being the NUL carrier or the SUL carrier; the terminal device receives a switching command from a source access network device, the switching command is used to indicate switching to the target cell; the terminal device uses the first carrier to perform a switching process to the target cell according to the carrier information.
  • the target access network device can determine whether to use NUL or SUL to complete the switching process for the target cell and indicate it to the terminal device, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a target access network device or by a module or unit (such as a chip or circuit) in the target access network device.
  • the target access network device is used for description below.
  • the method includes: the target access network device sends configuration information of the target cell to the terminal device, the configuration information of the target cell includes configuration information of the NUL carrier and configuration information of the SUL carrier; the target access network device sends a first message to the source access network device, and the first message is used to notify the terminal device that the configuration information of the NUL carrier and the configuration information of the SUL carrier are provided.
  • the target access network device can provide the terminal device with the configuration information of the NUL carrier and the configuration information of the SUL carrier of the target cell, and inform the source access network device of the configuration information of the NUL carrier and the configuration information of the SUL carrier of the target cell provided to the terminal device, so that the source access network device can determine whether to use NUL or SUL to complete the switching process of the target cell, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a source access network device or by a module or unit (such as a chip or circuit) in the source access network device.
  • the source access network device is used for description below.
  • the method includes: a source access network device receives a first message from a target access network device, the first message is used to notify a terminal device that configuration information of a NUL carrier and configuration information of a SUL carrier of a target cell are provided; the source access network device determines to use a first carrier to complete a switching process of the target cell; the source access network device sends a switching command to the terminal device, the switching command is used to indicate switching to the target cell, the switching command includes carrier information, the carrier information is used to indicate using the first carrier to complete a switching process of the target cell, the first carrier is the NUL carrier or the SUL carrier.
  • the source access network device can determine whether to use NUL or SUL to complete the switching process for the target cell, and instruct the terminal device through a switching command, which helps to ensure the successful cell switching.
  • a switching method is provided, which can be executed by a target access network device or by a module or unit (such as a chip or circuit) in the target access network device.
  • the target access network device is used for description below.
  • the method includes: the target access network device sends configuration information of the target cell to the terminal device, the configuration information of the target cell includes configuration information of the NUL carrier and configuration information of the SUL carrier; the target access network device sends carrier information to the source access network device, the carrier information is used to indicate the use of a first carrier to complete the switching process of the target cell, the first carrier is the NUL carrier or the SUL carrier.
  • the target access network device can provide the terminal device with the configuration information of the NUL carrier and the configuration information of the SUL carrier of the target cell, and inform the source access network device whether to use the NUL carrier or the SUL carrier to complete the switching process of the target cell, which helps to ensure the successful cell switching.
  • a switching method is provided, wherein the method can be executed by a source access network device or by a The method is executed by a module or unit (such as a chip or circuit), and the source access network device is used for description below.
  • the method includes: a source access network device receives carrier information from a target access network device, the carrier information is used to indicate the use of a first carrier to complete a switching process of a target cell, the first carrier is a NUL carrier of the target cell or a SUL carrier of the target cell; the source access network device sends a switching command to the terminal device, the switching command is used to indicate switching to the target cell, and the switching command includes the carrier information.
  • the target access network device can provide the terminal device with the configuration information of the NUL carrier and the configuration information of the SUL carrier of the target cell, and inform the source access network device whether to use the NUL carrier or the SUL carrier to complete the switching process of the target cell.
  • the source access network device can instruct the terminal device through a switching command whether to use the NUL carrier or the SUL carrier to complete the switching process of the target cell, which helps to ensure the successful cell switching.
  • a switching method is provided, which can be executed by a terminal device or by a module or unit (such as a chip or circuit) in the terminal device.
  • the terminal device is used for description below.
  • the method includes: a terminal device receives configuration information of a target cell from a target access network device, the configuration information of the target cell includes configuration information of a NUL carrier and configuration information of a SUL carrier; the terminal device receives a switching command from a source access network device, the switching command is used to indicate switching to the target cell, the switching command includes carrier information, the carrier information is used to indicate using a first carrier to complete a switching process of the target cell, the first carrier is the NUL carrier or the SUL carrier; the terminal device uses the first carrier to perform a switching process to the target cell according to the carrier information.
  • the source access network device can indicate whether to use NUL or SUL to complete the switching process for the target cell through a handover command, which helps to ensure the successful cell switching.
  • a switching method is provided.
  • the method can be executed by a terminal device or by a module or unit (such as a chip or circuit) in the terminal device.
  • the terminal device is used for description below.
  • the method includes: a terminal device receives configuration information of a target cell from a target access network device, the configuration information of the target cell includes configuration information of a NUL carrier and configuration information of a SUL carrier; the terminal device receives a switching command from a source access network device, the switching command is used to instruct switching to the target cell; the terminal device determines, based on the channel quality of the target cell, to use a first carrier to complete a switching process of the target cell, the first carrier being the NUL carrier or the SUL carrier; the terminal device uses the first carrier to perform a switching process to the target cell.
  • the terminal device can determine whether to use NUL or SUL to complete the switching process for the target cell, which helps to ensure the success of the cell switching.
  • the terminal device determines to use the first carrier to complete the switching process of the target cell based on the channel quality of the target cell, including: the terminal device determines to use the first carrier to complete the switching process of the target cell based on the channel quality of the target cell and a preset threshold value.
  • the terminal device determines to use the SUL carrier of the target cell to perform a switching process to the target cell, otherwise the terminal device determines to use the NUL carrier of the target cell to perform a switching process to the target cell.
  • the terminal device determines to use the SUL carrier of the target cell to perform the switching process to the target cell, otherwise the terminal device determines to use the NUL carrier of the target cell to perform the switching process to the target cell.
  • a communication device which is used to execute the method provided by any one of the above aspects or its implementation.
  • the device may include units and/or modules, such as a processing unit and/or a communication unit, for executing the method provided by any one of the above aspects or its implementation.
  • the device is a source CU, a target CU, a source access network device, a target access network device, or a terminal device.
  • the communication unit may be a transceiver, or an input/output interface, or a communication interface; the processing unit may be at least one processor.
  • the transceiver is a transceiver circuit.
  • the input/output interface is an input/output circuit.
  • the device is a chip, a chip system or a circuit used in a source CU, a target CU, a source access network device, a target access network device or a terminal device.
  • the communication unit may be an input/output interface, an interface circuit, an output circuit, an input circuit, a pin or a related circuit on the chip, the chip system or the circuit;
  • the processing unit may be at least one processor, a processing circuit or a logic circuit.
  • a communication device which includes: a memory for storing programs; and at least one processor for executing computer programs or instructions stored in the memory to execute the method provided by any one of the above aspects or its implementation.
  • the apparatus is a source CU, a target CU, a source access network device, a target access network device or a terminal device.
  • the device is a chip, a chip system or a circuit used in a source CU, a target CU, a source access network device, a target access network device or a terminal device.
  • a communication device comprising: at least one processor and a communication interface, the at least one processor is used to obtain a computer program or instruction stored in a memory through the communication interface to execute the method provided by any one of the above aspects or its implementation.
  • the communication interface can be implemented by hardware or software.
  • the device also includes the memory.
  • a processor for executing the methods provided in the above aspects.
  • a computer-readable storage medium which stores a program code for execution by a device, and the program code includes a method for executing any of the above aspects or its implementation method.
  • a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the method provided by any one of the above aspects or its implementation.
  • a chip comprising a processor and a communication interface, the processor reads instructions stored in a memory through the communication interface, and executes the method provided by any one of the above aspects or its implementation.
  • the communication interface can be implemented by hardware or software.
  • the chip also includes a memory, in which a computer program or instructions are stored, and the processor is used to execute the computer program or instructions stored in the memory.
  • the processor is used to execute the method provided by any one of the above aspects or its implementation methods.
  • the present application when the method provided by the present application is executed by a chip, the present application does not limit the number of chips that specifically implement the method of the present application. For example, it can be executed by one chip or by two or more chips. Moreover, when the number of chips that implement the method of the present application is two or more, the chip manufacturers are not limited and can be the same manufacturer or different manufacturers.
  • a communication system comprising at least one of the source CU, target CU, source access network device, target access network device or terminal device mentioned above.
  • a computer program which, when executed on a computer, enables the method provided by any one of the above aspects or its implementation to be executed.
  • FIG1 is a network architecture diagram applicable to an embodiment of the present application.
  • FIG2 is a schematic diagram of the CU-DU architecture.
  • FIG. 3 is a schematic flowchart of L1/L2 Triggered Mobility (LTM) switching between different DUs under the same CU.
  • LTM Triggered Mobility
  • FIG4 is a schematic flow chart of cell switching across base stations.
  • FIG. 5 is a schematic flow chart of a switching method 500 provided in the present application.
  • FIG. 6 is a schematic flowchart of a switching method 600 provided in the present application.
  • FIG. 7 is a schematic flowchart of a switching method 700 provided in the present application.
  • FIG. 8 is a schematic flowchart of a switching method 800 provided in the present application.
  • FIG. 9 is a schematic flowchart of a switching method 900 provided in the present application.
  • FIG. 10 is a schematic flowchart of a switching method 1000 provided in the present application.
  • FIG. 11 is a schematic diagram of the structure of a communication device provided in the present application.
  • FIG. 12 is another schematic diagram of the structure of the communication device provided in the present application.
  • Form indicating” or “for indicating” can include for direct indication and for indirect indication, or “for indicating” or “for indicating” It can be indicated explicitly and/or implicitly.
  • the first, second, and other digital numbers are only for the convenience of description and are not used to limit the scope of the embodiments of the present application, such as distinguishing different messages, different information, etc.
  • Pre-defined can be implemented by pre-saving the corresponding code, table or other methods that can be used to indicate relevant information in the device, and the present application does not limit its specific implementation method.
  • the "protocol” involved may refer to a standard protocol in the field of communication, such as the long term evolution (LTE) protocol, the new radio (NR) protocol, and related protocols used in future communication systems, and the present application does not limit this.
  • LTE long term evolution
  • NR new radio
  • Example for example, “exemplarily”, “as (another) example” and other words are used to indicate examples, illustrations or explanations. Any embodiment or design described as an “example” in this application should not be interpreted as being more preferred or more advantageous than other embodiments or design schemes.
  • the terms “including”, “comprising”, “having” and their variations all mean “including but not limited to”, unless otherwise specifically emphasized.
  • At least one means one or more, and “more than one” means two or more.
  • “And/or” describes the association relationship of associated objects, indicating that there may be three types of relationships. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.
  • a, b and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b and c. Where a, b and c can be single or multiple, respectively.
  • network element A sending a message, information or data to network element B
  • network element B receiving a message, information or data from network element A
  • description of network element A sending a message, information or data to network element B, and network element B receiving a message, information or data from network element A is intended to explain to which network element the message, information or data is to be sent, and does not limit whether they are sent directly or indirectly via other network elements.
  • the network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Ordinary technicians in this field can know that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.
  • the embodiments of the present application can be applied to various communication systems, such as LTE system, frequency division duplex (FDD) system, time division duplex (TDD) system, universal mobile telecommunication system (UMTS), worldwide interoperability for microwave access (WiMAX) communication system, fifth generation (5G) system or NR system, sixth generation (6G) system or future communication system, etc.
  • the 5G mobile communication system described in the present application includes a non-standalone (NSA) 5G mobile communication system or a standalone (SA) 5G mobile communication system.
  • the communication system may also be a public land mobile network (PLMN) network, a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an Internet of Things (IoT) communication system, a vehicle to everything (V2X) communication system, an uncrewed aerial vehicle (UAV) communication system or other communication systems.
  • PLMN public land mobile network
  • D2D device-to-device
  • M2M machine-to-machine
  • IoT Internet of Things
  • V2X vehicle to everything
  • UAV uncrewed aerial vehicle
  • FIG1 shows a network architecture diagram applicable to an embodiment of the present application.
  • the network architecture may specifically include three parts, namely, a terminal device part, a data network (DN) and an operator network part.
  • DN data network
  • the functions of the network elements of each part are briefly described below.
  • the terminal equipment part may include terminal equipment.
  • Terminal equipment may also be referred to as user equipment (UE), access terminal, terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, user agent or user device, etc. It is a device with wireless transceiver function, which can communicate with one or more core network (CN) devices via access network equipment (or also referred to as access equipment) in the radio access network (RAN).
  • CN core network
  • Terminal equipment can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; it can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (such as airplanes, balloons and satellites, etc.).
  • Terminal equipment can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a smart phone, a mobile phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), etc.
  • the terminal device may also be a handheld device with wireless communication function, a computing device or other device connected to a wireless modem, an in-vehicle device, a wearable device, an unmanned aerial vehicle device, or a terminal in the Internet of Things or Internet of Vehicles, a terminal in any form in a 5G network or future network, a relay user device, or a terminal in a future evolving 6G network, etc.
  • the terminal device may also be a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, or a wireless terminal in a smart grid.
  • VR virtual reality
  • AR augmented reality
  • the embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal device.
  • the data network also known as the packet data network (PDN)
  • PDN packet data network
  • the DN can also be deployed by the operator, that is, the DN is part of the PLMN.
  • the operator network can access multiple data network DNs, and a variety of services can be deployed on the data network DN, which can provide data and/or voice services to terminal devices.
  • the terminal device can also access the data network DN through the operator network, use the operator services deployed on the data network DN, and/or services provided by a third party.
  • the operator network part includes but is not limited to the (radio) access network ((radio) access network, (R)AN) part and the core network (core network, CN) part.
  • the access network device (RAN device) in the embodiment of the present application is a device that provides wireless communication functions for the terminal device.
  • the embodiments of the present application do not limit the specific technology and specific device form adopted by the access network device.
  • the access network device may be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next generation NodeB (gNB), a next generation base station in a 6th generation (6G) mobile communication system, an access node in a wireless fidelity (WiFi) system, or an access node in a base station in a future mobile communication system.
  • the access network device may be a macro base station, a micro base station or an indoor station, a relay node or a donor node, or a wireless controller in a CRAN scenario.
  • the access network device may also be a server, a wearable device, a vehicle or an onboard device.
  • the access network device in the vehicle to everything (V2X) technology may be a road side unit (RSU).
  • the access network device can be a CU, a DU, a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU).
  • the CU and the DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU).
  • BBU baseband unit
  • the RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).
  • CU or CU-CP and CU-UP
  • DU or RU may also have different names, but those skilled in the art can understand their meanings.
  • CU may also be called O-CU (open CU)
  • DU may also be called O-DU
  • CU-CP may also be called O-CU-CP
  • CU-UP may also be called O-CU-UP
  • RU may also be called O-RU.
  • CU, CU-CP, CU-UP, DU and RU are described as examples in this application.
  • Any unit of CU (or CU-CP, CU-UP), DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.
  • the CN part includes but is not limited to the following network functions (NF): user plane function (UPF), network exposure function (NEF), network function repository function (NRF), policy control function (PCF), UDM, UDR, access and mobility management function (AMF), session management function (SMF) and application function (AF).
  • NF network functions
  • UPF user plane function
  • NEF network exposure function
  • NRF network function repository function
  • PCF policy control function
  • UDM User Data Management Function
  • UDR access and mobility management function
  • AMF access and mobility management function
  • SMSF session management function
  • AF application function
  • UPF is the gateway for communication between the operator network and the data network DN. It mainly provides user-side functions such as forwarding and processing of user messages, connection with DN, session anchor point, and quality of service (QoS) policy execution.
  • QoS quality of service
  • NEF is a control plane function, which is mainly used to securely open the services and capabilities provided by 3GPP network functions to the outside world (such as AF). NEF also allows authenticated and authorized application functions to securely provide information in the 3GPP network.
  • NRF is a control plane function that can be used to maintain real-time information of network functions and services in the network.
  • PCF is the control plane function, which supports a unified policy framework to govern network behavior, provide policy rules to other control functions, contract information related to policy decisions, etc.
  • UDM is a control plane function, which is mainly responsible for storing the contract data of contracted users in the operator network.
  • UDR is a control plane function, which is mainly responsible for data storage and retrieval. For example, it provides the functions of storing and retrieving contract data for UDM, storing and retrieving policy data for PCF, and storing and retrieving user's NF group ID information.
  • AMF is a control plane function, which is mainly responsible for the access control and mobility management of terminal devices accessing the operator's network, such as mobile status management, allocation of user temporary identity, authentication and authorization of users, etc.
  • SMF is the control plane function, which is mainly responsible for session management (such as session establishment, modification and release), selection and control of UPF network functions, service and session continuity (SSC) mode selection, roaming and other session-related functions.
  • session management such as session establishment, modification and release
  • SSC service and session continuity
  • AF is a control plane function used to provide application layer information.
  • Nnef, Nnrf, Npcf, Nudm, Nudr, Namf, Nsmf, N1, N2, N3, N4, N6 and N9 are interface serial numbers.
  • the meaning of the above interface serial numbers can be found in the meaning defined in the 3GPP standard protocol, and this application does not limit the meaning of the above interface serial numbers.
  • the interface name between the various network functions in Figure 1 is only an example. In the specific implementation, the interface name of the system architecture may also be other names, which is not limited in this application.
  • the interface between each network element can be a point-to-point interface or a service-oriented interface, which is not limited in this application.
  • network architecture shown above is only an exemplary description, and the network architecture applicable to the embodiments of the present application is not limited thereto. Any network architecture that can realize the functions of the above-mentioned network elements is applicable to the embodiments of the present application.
  • the functions or network elements such as AMF, SMF, UPF, PCF, UDM, UDR, NEF, NRF, AF, etc. shown in Figure 1 can be understood as network elements used to implement different functions, for example, they can be combined into network slices as needed.
  • These network elements can be independent devices, or they can be integrated into the same device to implement different functions, or they can be network elements in hardware devices, or they can be software functions running on dedicated hardware, or they can be virtualized functions instantiated on a platform (for example, a cloud platform). This application does not limit the specific form of the above network elements.
  • FIG2 is a schematic diagram of the CU-DU architecture.
  • the base station can be logically divided into a CU and one or more DUs. Each DU is connected to the CU through the F1 logical interface.
  • the operations related to the Radio Link Control (RLC) layer, the Media Access Control (MAC) layer, and the Physical Layer (PHY) are processed by the DU, and the operations related to the Service Data Adaptation Protocol (SDAP) layer, the Radio Resource Control (RRC) layer, and the Packet Data Convergence Protocol (PDCP) layer are processed by the CU.
  • RLC Radio Link Control
  • MAC Media Access Control
  • PHY Physical Layer
  • SDAP Service Data Adaptation Protocol
  • RRC Radio Resource Control
  • PDCP Packet Data Convergence Protocol
  • L1 in LTM refers to PHY
  • L2 refers to the MAC layer, RLC layer, PDCP layer and SDAP layer.
  • the terminal device sends the L1 measurement results to the base station through physical layer control signaling, where the physical layer control signaling can be carried on the physical uplink control channel (PUCCH); the physical layer of the base station reads the L1 measurement results, and makes a switching decision based on the L1 measurement results, and then sends the switching decision to the terminal device through L1/L2 signaling, where the L1/L2 signaling can be a message carried on the physical downlink control channel (PDCCH) or a MAC control element (MAC CE).
  • PUCCH physical uplink control channel
  • MAC CE MAC control element
  • L1/L2 represents L1 and/or L2.
  • the operations related to the switching process are mainly completed by L1 and L2; when it is an "or” relationship, the operations related to the switching process are mainly completed by L1 or L2.
  • FIG 3 is a schematic flowchart of LTM switching between different DUs under the same CU.
  • S-DU refers to the source DU
  • T-DU refers to the target DU
  • the source DU and the target DU belong to the same CU.
  • the target DU is one of the candidate DUs.
  • a candidate DU becomes the target DU.
  • Figure 3 only shows the signaling interaction between the CU and the target DU.
  • Step 301 The CU obtains candidate cell configuration information from the candidate DU.
  • the CU obtains the configuration information of the candidate cells under each candidate DU.
  • a complete candidate cell configuration information may include a part generated by the CU and a part generated by the DU.
  • the part generated by the CU may be described as "CU side configuration information” and the part generated by the DU may be described as "DU side configuration information”.
  • the candidate cell configuration information here refers to "DU side configuration information”.
  • Step 302 The CU sends the candidate cell configuration information to the terminal device via the source DU.
  • the candidate cell configuration information here may refer to complete candidate cell configuration information, namely, "CU side configuration information” and "DU side configuration information”.
  • Step 303 The terminal device performs cell measurement and reports the measurement result to the source DU.
  • the terminal device reports the L1 measurement result, and the terminal device sends the L1 measurement results of different cells to the source DU through the communication resources of the source cell.
  • the L1 measurement result includes at least one of the following: the L1 measurement result of the source cell, or the L1 measurement result of at least one candidate cell.
  • the L1 measurement results of the above-mentioned source cell and/or candidate cell may be cell-level measurement results or beam-level measurement results.
  • Step 304 The source DU determines to switch the terminal device to the target cell based on the L1 measurement result reported by the terminal device, and sends a switching command to the terminal device.
  • the target cell is one of the candidate cells.
  • the handover command includes identification information of the target cell.
  • the handover command can be sent to the terminal device via L1/L2 signaling, and the L1/L2 signaling is still sent via the communication resources of the source cell.
  • the L1/L2 signaling can be a MAC CE.
  • the source DU may also send the situation that triggered the cell switching to the CU.
  • Step 305 The terminal device performs LTM switching to the target cell.
  • the terminal device uses the configuration information of the target cell received in step 302 to access the target cell.
  • the terminal device After the terminal device successfully accesses the target cell, the terminal device transmits uplink and downlink data with the target cell.
  • Step 306 After the terminal device successfully accesses the target cell, the target DU sends a switching success notification to the CU to notify the terminal device of successful switching to the target cell.
  • the base station will pre-configure the configuration information of the candidate cells to the terminal device.
  • the downlink data sent to the terminal device is sent by the UPF of the core network to the base station, and then sent by the base station to the terminal device.
  • the movement of a terminal device may cause a change in the communication link between the terminal device and a base station.
  • the base station will instruct the terminal device to perform a cell switch according to the movement of the terminal device.
  • a user plane transmission bearer is established between the UPF and the source base station.
  • Downlink data can be sent to the source base station through the user plane transmission bearer between the UPF and the source base station, and further sent to the terminal device by the source base station.
  • the source base station will send a switch command to the terminal device. After that, the source base station can no longer send downlink data from the UPF to the terminal device.
  • the source base station can send the downlink data cached in the source base station to the target base station so that after the switch is completed, the target base station can send it to the terminal device, thereby ensuring data losslessness.
  • the process of forwarding data from the source base station to the target base station is called data forwarding.
  • the above-mentioned user plane transmission bearer may also be described as a user plane channel, a user plane tunnel, a user plane data channel or a user plane data tunnel, etc.
  • the target base station can send the data forwarded by the source base station to the terminal device.
  • the target base station needs to send a path switch request message to the AMF of the core network to request the establishment of a user plane transmission bearer between the UPF and the target base station.
  • the AMF can control the UPF to establish a user plane transmission bearer with the target base station.
  • the UPF can send downlink data directly to the target base station without forwarding data through the source base station.
  • Fig. 4 is a schematic flow chart of cell switching across base stations. Fig. 4 is illustrated by taking transmission of downlink data as an example.
  • Step 401 When the source base station determines that the terminal device needs to be switched, the source base station sends a switching request message to the target base station.
  • Step 402 When the target base station allows the terminal device to access, the target base station sends a handover request response message to the source base station.
  • the handover request response message may include configuration information of the target cell.
  • Step 403 After receiving the handover request response message, the source base station sends a handover command to the terminal device.
  • the switching command includes the configuration information of the target cell.
  • Step 404 After the source base station sends a switching command to the terminal device, the source base station forwards the downlink data from the UPF to the target base station.
  • the source base station After the source base station sends a switching command to the terminal device, the source base station can no longer send downlink data to the terminal device.
  • the source base station sends the downlink data cached in the source base station to the target base station so that the target base station can send it to the terminal device after the terminal device accesses the target cell.
  • Step 405 The terminal device accesses the target cell using the configuration information of the target cell according to the received switching command.
  • Step 406 After the terminal device successfully accesses the target cell, the target base station sends a path switching request message to the AMF.
  • Step 407 AMF controls UPF to perform path switching and establishes a user plane transmission bearer between UPF and the target base station.
  • Step 408 After step 407, the UPF can send the downlink data sent to the terminal device to the target base station without forwarding the data through the source base station.
  • Step 409 AMF sends a path switching request response message to the target base station.
  • Step 410 The target base station sends data to the terminal device.
  • the downlink data includes downlink data forwarded by the source base station and downlink data directly from the UPF. It should be noted that the target base station can send the downlink data forwarded by the source base station to the terminal device after step 405.
  • step 404 shows data forwarding during cell switching across base stations
  • steps 406 to 409 show path switching during cell switching across base stations.
  • a downlink data needs to be sent from UPF to the terminal device within a specific time, for example, within 20ms.
  • some data needs to go through the data forwarding process from the source base station to the target base station. This additional delay may cause these data (especially the data of delay-sensitive services) to reach the terminal device after exceeding the specific time. Data that exceeds this specific time will become invalid and unavailable to the terminal device, which will cause a decline in service experience.
  • the present application provides a switching method, which can reduce the data forwarded from the source CU to the target CU by advancing the path switching process, thereby reducing invalid data and improving the service experience.
  • the embodiments of the present application can be applied to LTM switching between different DUs under different CUs, and can also be applied to other similar switching scenarios and switching technologies without limitation. It should be noted that the numbering of the steps in the following method embodiments does not mean the order of execution. The order of the steps can be determined by the internal logic, and the order of the steps described below is only an example and is not limited to this.
  • Fig. 5 is a schematic flow chart of a switching method 500 provided in the present application.
  • the method 500 includes at least part of the following contents.
  • Step 501 Receive a first notification message.
  • the first notification message is used to indicate the target cell to which the terminal device will switch.
  • the target cell is the cell of the target DU under the target CU.
  • Step 502 Send a first request message to a core network device according to the first notification message.
  • the first request message is used to request that the user plane bearer of the terminal device be switched to the target CU.
  • the user plane bearer can also be described as a user plane transmission bearer, a user plane channel or a user plane tunnel.
  • the user plane bearer of the terminal device can be understood as a bearer, a channel or a tunnel used to transmit the user plane data of the terminal device.
  • method 500 can initiate the switching of the user plane bearer of the terminal device according to the first notification message used to indicate the target cell to which the terminal device will switch.
  • the switching of the user plane bearer of the terminal device can be triggered by the first notification message, so that the switching of the user plane bearer of the terminal device can be performed earlier.
  • the service data of the terminal device can be sent directly to the target CU without going through the data forwarding process from the source CU to the target CU. Therefore, based on method 500, the data forwarded from the source CU to the target CU can be reduced, thereby reducing invalid data and improving the service experience.
  • Method 500 may be executed by a source CU or a module or unit in the source CU, or may be executed by a target CU or a module or unit in the target CU. The following description will uniformly use the source CU or the target CU.
  • Fig. 6 is a schematic flow chart of a switching method 600 provided in the present application.
  • the method 600 may include at least part of the following contents.
  • Step 601 The source DU sends a notification message #1 to the source CU, or in other words, the source CU receives the notification message #1 from the source DU.
  • notification message #1 may correspond to the first notification message in method 500, which is used to indicate the target cell to which the terminal device will switch.
  • Notification message #1 is used to indicate the target cell to which the terminal device will switch, and can also be described as: notification message #1 is used to indicate that the terminal device will switch to the target cell, or the first notification message is used to notify the source CU of the initiation of the LTM command for the terminal device and the identification of the target cell.
  • the source DU may determine to switch the terminal device to the target cell based on the L1 measurement result reported by the terminal device, and after determining to switch the terminal device to the target cell, send a notification message #1 to the source CU.
  • Step 602 The source CU sends a request message #1 to the core network device according to the notification message #1.
  • request message #1 can correspond to the first request message in method 500, which is used to request to switch the user plane bearer of the terminal device to the target CU.
  • the request message #1 may be a path switching request message.
  • Request message #1 is used to request that the user plane bearer of the terminal device be switched to the target CU, and can also be replaced by: Request message #1 is used to request that the downlink termination point of the user plane transmission bearer of the terminal device be switched to the downlink termination point of the user plane transmission bearer corresponding to the target cell, wherein the downlink termination point of the user plane transmission bearer corresponding to the target cell can be the target CU to which the target cell belongs.
  • the core network device may be an AMF.
  • the AMF may control the UPF to switch the user plane bearer of the terminal device to the target CU.
  • the source CU can initiate the switching of the user plane bearer of the terminal device based on the notification message #1 used to indicate the target cell to which the terminal device will switch, and can execute the switching process of the user plane bearer of the terminal device earlier, thereby reducing the data forwarded from the source CU to the target CU, thereby reducing invalid data and improving the service experience.
  • the notification message #1 includes the first identifier of the target cell.
  • Step 602 may specifically include: the source CU sends a request message #1 to the core network device according to the first identifier of the target cell in the notification message #1 and the first association relationship, wherein the first association relationship is used to indicate the association relationship between the first identifier of the target cell and the first information, the first information is used to indicate the channel information carried by the user plane of the target CU, and the request message #1 may include the first information.
  • the first information may include at least one of the following information: an IP address of a downlink termination point of a user plane bearer of the target CU, or a GTP-TEID of a downlink termination point of a user plane bearer of the target CU.
  • the first information is used to indicate the channel information carried by the user plane of the target CU, and can also be replaced by: the first information is used to indicate the channel information carried by the user plane corresponding to the target cell.
  • each cell managed by a CU can correspond to a channel information carried by a user plane, or a cell managed by a candidate CU can also correspond to the same channel information carried by the user plane, without limitation.
  • the embodiments of the present application do not limit the method for obtaining the first association relationship.
  • the first association relationship is preconfigured.
  • method 600 may further include steps 603-605, which are specifically as follows.
  • Step 603 The source CU sends a request message #2 to the target CU, or the target CU receives the request message #2 from the source CU.
  • request message #2 is used to request the channel information carried by the user plane of the target CU, that is, the above-mentioned first information.
  • request message #2 may be a multiplexing or enhancement of a message for requesting candidate cell configuration information.
  • the source CU may request the channel information carried by the user plane of the target CU at the same time as requesting the candidate cell configuration information from the target CU.
  • the request for the channel information carried by the user plane of the target CU may be explicit or implicit, without restriction.
  • the source CU may add additional information to the message for requesting candidate cell configuration information, such as the identifier of the target CU, to indicate the channel information carried by the user plane of the target CU.
  • the source CU may send a message for requesting candidate cell configuration information, and the message itself may indicate the channel information carried by the user plane of the target CU.
  • Step 604 After receiving the request message #2, the target CU sends a response message of the request message #2 to the source CU, that is, the response message #2 in Figure 6. Accordingly, the source CU receives the response message #2 from the target CU.
  • response message #2 includes the first information.
  • Step 605 The source CU determines a first association relationship according to the first information.
  • the source CU determines the first association relationship based on the target cell, the cell managed by the target CU, and the first information.
  • the source CU can generate an association relationship between the cell managed by the target CU and the first information after receiving the first information. Since the cell managed by the target CU includes the target cell, the generated association relationship includes the first association relationship.
  • the response message #2 also includes a second identifier of the target cell.
  • the source CU can generate a first association relationship based on the second identifier of the target cell and the first information in the response message #2.
  • the first identifier of the target cell can be an identifier of the target cell on the air interface
  • the second identifier of the target cell can be an identifier of the target cell on the network side.
  • the first identifier of the target cell and the second identifier of the target cell can be the same or different.
  • the length of the first identifier of the target cell is smaller than the length of the second identifier of the target cell. In this way, the signaling overhead of the air interface can be reduced.
  • the source CU For the case where the first identifier of the target cell and the second identifier of the target cell are different, the source CU generates a first association relationship based on the second identifier of the target cell and the first information in the response message #2, which may specifically include: the source CU may convert the second identifier of the target cell included in the response message #2 into the first identifier, and then generate an association relationship between the first identifier and the first information, i.e., the first association relationship.
  • steps 603-605 may involve signaling interaction between the source CU and at least one candidate CU including the target CU, and involve determining the association relationship between the channel information carried by the user plane of at least one candidate cell including the target cell and the corresponding candidate CU.
  • method 600 may further include step 606: the source CU sends at least one association relationship to the target CU, or the target CU receives at least one association relationship from the source CU.
  • at least one association relationship is an association relationship between at least one candidate cell generated by steps 603-605 and the channel information carried by the user plane of the corresponding candidate CU, and at least one association relationship includes the above-mentioned first association relationship.
  • FIG6 only takes the example of the source CU sending at least one association relationship to the target CU.
  • the source CU may send the at least one association relationship to all candidate CUs.
  • the source CU may send at least one association relationship to the candidate cell after determining at least one association relationship.
  • the source CU may send at least one association relationship to the target CU and/or the candidate CU after learning that the terminal device successfully accesses the target cell.
  • Step 602 may specifically include: the source CU sends a request message #1 to the core network device according to the first identifier of the target cell in the notification message #1 and the second association relationship, wherein the second association relationship is used to indicate the association relationship between the target CU and the first information, and the first information is used to indicate the channel information carried by the user plane of the target CU, and the request message #1 may include the first information.
  • the source CU determines the identifier of the target CU to which the target cell belongs based on the first identifier of the target cell in notification message #1 and the cell managed by the target CU, and then sends a request message #1 to the core network device based on the identifier of the target CU and the second association relationship.
  • the embodiments of the present application do not limit the method for obtaining the second association relationship.
  • the second association relationship is preconfigured. Similar to the acquisition method of the first association relationship, reference may be made to steps 603-605, except that the response message #2 may include the identifier of the target CU and the first information, so that the source CU may generate a correspondence between the identifier of the target CU and the first information.
  • method 600 may further include: the source CU sends at least one association relationship to the target CU, or the target CU receives at least one association relationship from the source CU.
  • the association relationship is an association relationship between the candidate CU and the channel information carried by its user plane, and at least one association relationship includes the above-mentioned second association relationship.
  • method 600 may also include step 607: the source CU sends the correspondence between the first identifier of the target cell and the second identifier of the target cell to the target CU, so that the target CU knows the correspondence between the first identifier of the target cell and the second identifier of the target cell.
  • FIG6 only takes the correspondence between the first identifier of the target cell and the second identifier of the target cell sent by the source CU to the target CU as an example.
  • the source CU can send the correspondence between the first identifier and the second identifier of all candidate cells to each CU in all candidate CUs.
  • multiple CUs including the source CU and the target CU can use the same first identifier of the candidate cell when communicating with the terminal, thereby avoiding repeated configuration of the terminal device.
  • This application does not limit the implementation method of sending the correspondence between the first identifier of the target cell and the second identifier of the target cell.
  • the correspondence between the first identifier of the target cell and the second identifier of the target cell can be sent to the candidate CU together with at least one association relationship.
  • the source CU knows the cells managed by the candidate CU, the source CU can convert the candidate cell identity in advance and carry the correspondence between the first identifier of the target cell and the second identifier of the target cell in the request message #2 of step 603.
  • the switching of the user plane bearer of the terminal device initiated by the source CU may be specified by the protocol or determined by negotiation between the source CU and the target CU. The following describes the negotiation between the source CU and the target CU.
  • This application does not limit the specific implementation method of the negotiation between the source CU and the target CU.
  • the source CU may carry second information in the request message #2 in step 603, and the second information is used to request the The source CU initiates the switching of the user plane bearer of the terminal device, that is, the path switching.
  • the target CU may carry the third information in the response message #2 of step 604, and the third information is used to indicate that the switching of the user plane bearer of the terminal device is allowed to be initiated by the source CU.
  • the source CU may determine that the switching of the user plane bearer of the terminal device is initiated by itself.
  • the source CU may carry fourth information in the request message #2 of step 603, and the fourth information is used to indicate that the switching of the user plane bearer of the terminal device is initiated by the source CU.
  • the source CU determines that the switching of the user plane bearer of the terminal device is initiated by itself and then notifies the target CU without the permission of the target CU.
  • method 600 may further include steps 608 and 609, as described below.
  • Step 608 After receiving notification message #1, the source CU sends notification message #2 to the target CU, or in other words, the target CU receives notification message #2 from the source CU.
  • notification message #2 is used to indicate the target cell to which the terminal device will switch, or to indicate that the terminal device will switch to the target cell.
  • notification message #2 may include at least one of the following information: a first identifier of the target cell, beam information, or access information.
  • the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal device.
  • the access information is used to indicate the access method used by the terminal device to access the target cell, such as an access method based on random access or an access method based on random access-free access.
  • Step 609 After receiving notification message #2, the target CU sends notification message #3 to the target DU, or in other words, the target DU receives notification message #3 from the target CU.
  • notification message #3 is used to indicate the target cell to which the terminal device will switch, or to indicate that the terminal device will switch to the target cell.
  • the notification message #3 may include at least one of the following information: a first identifier of the target cell, beam information, or access information, so that the target DU uses this information to perform an access process with the terminal device.
  • the notification message #2 in step 608 may further include seventh information, wherein the seventh information is used to indicate that the source CU has initiated the switching of the user plane bearer of the terminal device.
  • the notification message #2 may carry the seventh information so that the target CU does not initiate the switching of the user plane bearer of the terminal device according to the seventh information.
  • method 600 may further include steps 610 and 611, as follows.
  • Step 611 after receiving service data #1, the target CU sends service data #1 to the target DU.
  • the target CU may send service data #1 to the target DU after receiving notification message #2.
  • the target DU may immediately send data to the terminal device, thereby facilitating the sending of data to the terminal device as soon as possible and avoiding data failure.
  • the method 600 may further include step 614: the target CU receives a notification message #5 from the core network device, where the notification message #5 is used to indicate one of the following information:
  • PDU protocol data unit
  • ID the protocol data unit (PDU) session identifier (ID) of the successfully completed user plane bearer switching, and the channel information of the uplink user plane bearer corresponding to the PDU session ID;
  • request message #1, request message #2, response message #1, response message #2, notification message #1, notification message #2, notification message #3, notification message #4, notification message #5, and notification message #6 can also be numbered as the first request message, the second request message, the first response message, the second response message, the first notification message, the second notification message, the sixth notification message, the fourth notification message, Seventh notification message, fifth notification message.
  • Fig. 7 is a schematic flow chart of a switching method 700 provided in the present application.
  • the method 700 may include at least part of the following contents.
  • Step 701 The source DU sends a notification message #7 to the source CU, or the source CU receives the notification message #7 from the source DU. Step 701 may refer to step 601 and will not be described in detail.
  • Step 702 After receiving notification message #7, the source CU sends notification message #8 to the target CU, or in other words, the target CU receives notification message #8 from the source CU.
  • notification message #8 may correspond to the first notification message in method 500, which is used to indicate the target cell to which the terminal device will switch.
  • Notification message #8 is used to indicate the target cell to which the terminal device will switch, and can also be described as: notification message #1 is used to indicate that the terminal device will switch to the target cell, or the first notification message is used to notify the source CU of the initiation of the LTM command for the terminal device and the identification of the target cell.
  • Step 703 The target CU sends a request message #3 to the core network device according to the notification message #8.
  • Request message #3 may correspond to the first request message in method 500, and is used to request switching of the user plane bearer of the terminal device to the target CU.
  • the description of request message #3 may refer to request message #1, and will not be described in detail here.
  • the implementation method of the target CU sending the request message #3 to the core network device can refer to the path switching process in the existing standard and will not be described in detail.
  • the core network device may be AMF.
  • AMF may control UPF to switch the user plane bearer of the terminal device to the target CU.
  • the target CU can initiate the switching of the user plane bearer of the terminal device based on the notification message #8 used to indicate the target cell to which the terminal device will switch, and can execute the switching process of the user plane bearer of the terminal device earlier, thereby reducing the data forwarded from the source CU to the target CU, thereby reducing invalid data and improving the service experience.
  • the switching of the user plane bearer of the terminal device initiated by the target CU may be specified by the protocol, or may be determined by negotiation between the source CU and the target CU.
  • This application does not limit the specific implementation method of the negotiation between the source CU and the target CU.
  • method 700 may include steps 704 and 705, as follows.
  • Step 704 The source CU sends a request message #4 to the target CU, or the target CU receives the request message #4 from the source CU.
  • Request message #4 is used to request the first information, and the first information is used to indicate the channel information of the user plane bearer of the target CU.
  • the description of request message #4 can refer to request message #2.
  • the first information can refer to the description in step 602.
  • the source CU may carry second information in the request message #4 of step 704, where the second information is used to request the source CU to initiate switching of the user plane bearer of the terminal device, that is, path switching.
  • Step 705 after receiving request message #4, the target CU sends a response message of request message #4 to the source CU, that is, response message #4 in FIG. 7 .
  • the response message #4 includes the sixth information.
  • the sixth information is used to indicate that the source CU is not allowed to initiate the switching of the user plane bearer of the terminal device. In this case, the target CU subsequently initiates the switching of the user plane bearer of the terminal device.
  • steps 704-705 may involve signaling interaction between the source CU and at least one candidate CU including the target CU. If there are other candidate CUs that allow the source CU to initiate user plane bearer switching of the terminal device and provide the source CU with the channel information of its user plane bearer, the source CU can determine the association relationship between the candidate cell of the candidate CU and the channel information of the user plane bearer of the candidate cell, or determine the association relationship between the candidate CU and the channel information of the user plane bearer of the candidate cell.
  • the specific implementation method can refer to steps 603-605.
  • the source CU may send the determined association relationship to at least one candidate CU including the target CU. Based on this, when the target CU is used as the source CU of the subsequent switching, it is not necessary to re-execute steps 704-705, thereby reducing the signaling overhead, so that the subsequent switching process and the corresponding path switching process can be executed faster.
  • the method 700 may further include step 706: the source CU sends the corresponding relationship between the first identifier of at least one candidate cell and the second identifier of at least one candidate cell to the target CU, and the specific implementation method may refer to step 607.
  • the specific implementation method may refer to step 607.
  • the notification message #8 in step 702 may also include at least one of the following information: a first identifier of the target cell, beam information, or access information.
  • the beam information is used to indicate the beam direction used by the target cell to communicate with the terminal device.
  • the access information is used to indicate the access method used by the terminal device to access the target cell, such as an access method based on random access, or an access method based on random access-free access.
  • method 700 may also include step 707: after receiving notification message #8, the target CU sends notification message #9 to the target DU, or the target DU receives notification message #9 from the target CU.
  • notification message #9 is used to indicate the target cell to which the terminal device will switch, or to indicate that the terminal device will switch to the target cell.
  • notification message #9 may include at least one of the following information: a first identifier of the target cell, beam information, or access information, so that the target DU uses this information to perform an access process with the terminal device.
  • the notification message #8 in step 702 may further include fifth information, wherein the fifth information is used to indicate that the source CU did not initiate the switching of the user plane bearer of the terminal device.
  • the notification message #8 may carry the fifth information so that the target CU initiates the switching of the user plane bearer of the terminal device.
  • method 700 may further include steps 708 and 709, as described below.
  • Step 708 The source CU forwards the service data #2 of the terminal device cached in the source CU to the target CU according to the notification message #7, so that the target base station can send the service data #2 to the terminal device after the terminal device accesses the target cell.
  • Step 709 After receiving service data #2, the target CU sends service data #2 to the target DU.
  • the target CU may send service data #2 to the target DU after determining that the terminal device has successfully accessed the target cell.
  • the target CU may send service data #2 to the target DU after receiving the notification message #10 as shown in step 710, wherein the notification message #10 is used to indicate that the terminal device has successfully accessed the target cell. This can avoid invalid transmission of service data #2 to the target DU.
  • the response message #A may also include at least one of the following information: the identity of the candidate cell, or the indication information #4.
  • the indication information #4 is used to indicate that the candidate CU does not allow the path switching to be initiated by the source CU.
  • the response message #A may also include at least one of the following information: the identity of the candidate cell, or the channel information of the user plane bearer of the candidate CU.
  • the source CU can subsequently initiate a path switch. If the response message #A includes indication information #3, that is, the candidate CU allows the source CU to initiate a path switch, the source CU can subsequently initiate a path switch. If the response message #A includes indication information #4, that is, the candidate CU does not allow the source CU to initiate a path switch, the candidate CU can subsequently initiate a path switch.
  • the above-mentioned candidate cell identity is information that can uniquely identify the candidate cell.
  • the identity information of the candidate cell may include at least one of the candidate cell's global cell identifier (CGI) or physical cell ID (PCI).
  • CGI global cell identifier
  • PCI physical cell ID
  • the channel information carried by the user plane of the candidate CU mentioned above may also be referred to as the tunnel information carried by the user plane of the candidate CU, which is used to indicate the termination point of the data sent by the UPF to the candidate CU.
  • the channel information carried by the user plane may be NG-U user plane transport network layer information (NG-U user plane transport network layer information, NG-U UP TNL Information), where NG-U is the interface name between the UPF and the CU, which is the interface name defined in the protocol, and NG-U refers to the next generation user plane (next generation-user plane).
  • the channel information carried by the user plane may include at least one of the following information: the IP address of the termination point, or the GTP-TEID of the termination point.
  • the user plane bearer of the candidate CU may refer to the PDU session of the candidate CU.
  • each PDU session in the PDU session of the same candidate CU may correspond to the channel information of a user plane bearer, for example, different service types correspond to different PDU sessions, and each PDU session has its own user plane bearer channel information.
  • the PDU session of the same candidate CU may also correspond to the same user plane bearer channel information.
  • FIG8 only shows the signaling interaction between the target DU and the target CU selected as the target cell in the candidate cell.
  • steps 801 to 804 may involve signaling interaction between one or more candidate CUs and one or more candidate DUs.
  • Step 805 Based on the response message #A of each candidate CU, the source CU may determine the association relationship between the candidate cell and the channel information of the user plane bearer of the candidate CU corresponding to the candidate cell.
  • the source CU may determine that the path switching is initiated by the source CU based on the indication information #3 in the response message #A, and then The identity information of the candidate cell in information #A and the channel information of the user plane bearer of the candidate CU are used to determine the association relationship between the candidate cell and the channel information of the user plane bearer of the candidate CU corresponding to the candidate cell.
  • the source CU may generate an association relationship between the identity of the candidate cell included in the response message #A and the channel information carried by the user plane of the corresponding candidate CU.
  • the source CU may convert the identity of the candidate cell included in the response message #A into a new identity, and then generate an association relationship between the new identity and the channel information carried by the user plane of the candidate CU.
  • the source CU can convert the CGI or PCI of the candidate cell into a shorter candidate cell ID, such as an ID with a value range of 0-7; and then generate an association between the candidate cell ID and the channel information carried by the user plane of the candidate CU.
  • the source CU can use the candidate cell ID to communicate with the terminal device and/or other network elements in subsequent communications. In this way, the signaling overhead can be reduced, and the exposure of the true identity information of the candidate cell on the air interface can be avoided, making the communication system more secure.
  • the candidate CU since the candidate CU does not allow the source CU to initiate path switching, the candidate CU does not provide the source CU with the channel information carried by its user plane. Therefore, the source CU will not determine the association relationship between the candidate cell managed by the candidate CU and the channel information carried by the user plane of the candidate CU. In other words, after step 805, there is no association relationship between the candidate cell managed by the candidate CU and the channel information carried by the user plane of the candidate CU in the source CU.
  • Step 806 The source CU sends the received candidate cell configuration information to the terminal device, or the terminal device receives the candidate cell configuration information from the source CU.
  • Step 807 The source DU determines to switch the terminal device to the target cell.
  • step 806 and step 807 the step of the terminal device reporting the measurement results of the candidate cell and the serving cell may be performed, which is not shown in Figure 8.
  • the source DU may determine the target cell from the candidate cells according to the measurement results reported by the terminal device.
  • Step 808 The source DU sends a switching command to the terminal device, or the terminal device receives a switching command from the source DU.
  • the handover command includes the identity of the target cell, such as the candidate cell ID generated by the source CU in step 805. At this time, the candidate cell ID becomes the target cell ID.
  • Step 809 The source DU sends a notification message #A to the source CU, or the source CU receives a notification message #A from the source DU.
  • the notification message #A is used to indicate that the terminal device will switch to the target cell.
  • the notification message #A includes the identity of the target cell, such as the candidate cell ID generated by the source CU in step 805. At this time, the candidate cell ID becomes the target cell ID.
  • Case 1 the response message #A sent by the target CU includes indication information #3, that is, the candidate CU permits the source CU to initiate path switching. In this case, steps 810-817 can be executed.
  • Step 810 The source CU sends a path switching request message to the AMF according to the notification message #A, or in other words, the AMF receives a path switching message from the source CU.
  • the path switch request message is used to request to switch the user plane bearer of the terminal device to the target CU.
  • the path switch request message may include the channel information of the user plane bearer corresponding to the target cell and the identity of the terminal device.
  • the identity of the terminal device may be a RAN UE next generation application protocol ID (RAN UE NGAP ID).
  • the source CU can obtain the identity of the target cell based on the notification message #A, and further obtain the channel information carried by the user plane of the target CU based on the association relationship between the identity of the target cell and the channel information carried by the user plane of the target CU, such as the association relationship generated in step 805, and then send the channel information carried by the user plane of the target CU and the identity of the terminal device to the AMF through a path switching request message.
  • the present application does not limit the timing when the source CU sends the path switching request message.
  • the source CU may send downlink data that has not yet been sent to the terminal device and/or data that has not yet been successfully sent to the terminal device to the target CU.
  • the data that has not yet been successfully sent to the terminal device may include data that has been sent to the terminal device but for which feedback of successful reception by the terminal device has not yet been received.
  • the source CU forwards the uplink data from the terminal device to the target CU.
  • Case 2 the response message #A sent by the target CU includes indication information #4, that is, the candidate does not allow the path switching initiated by the source CU. In this case, steps 818-824 can be executed.
  • Step 818 After receiving the notification message #A, the source CU may send the data of the terminal device to the target CU, or the target CU receives the data from the source CU.
  • the source CU may send the data of the terminal device to the target CU, or the target CU receives the data from the source CU.
  • the target CU receives the data from the source CU.
  • the source CU may also send a notification message #C to the target CU based on the notification message #A, or in other words, the target CU receives the notification message #C from the source CU.
  • the notification message #C includes at least one of the following information: the identity of the target cell, beam information or access information.
  • the beam information is used to indicate the beam direction used when the target cell communicates with the terminal device.
  • the access information is used to indicate the access method used by the terminal device to access the target cell.
  • the access method used by the terminal device to access the target cell is any one of the following: random access method or random access-free method.
  • the notification message #C also includes indication information #6, wherein the indication information #6 is used to indicate that the source CU did not initiate the path switch, the source CU did not perform the path switch, the source CU did not perform the step of sending a path switch request message, or the path switch was initiated by the target CU.
  • Step 820 after receiving the notification message #C, the target CU sends a path switching request message to the AMF according to the identity of the target cell in the notification message #C, or in other words, the AMF receives the path switching message from the target CU.
  • Another possible implementation method is that if the notification message #C includes indication information #6, the target CU can determine the Perform path switching, thereby sending a path switch request message to AMF.
  • the present application does not limit the timing when the target CU sends the path switching request message.
  • a possible implementation method, as shown in Figure 8, is that the target CU can send a path switching request message immediately after receiving the notification message #C, or, the path switching initiated by the target CU can be triggered by the notification message #C, or, in response to the notification message #C, the target CU sends a path switching request message.
  • the target CU may initiate a path switch after the terminal device successfully accesses the target DU, or after the terminal device successfully switches to the target cell of the target DU.
  • Step 821 after receiving the path switching request message, AMF and UPF perform path switching.
  • the implementation method of path switching by AMF and UPF can refer to the existing protocol and will not be described in detail here.
  • the method 800 may further include step 822, that is, the AMF sends a path switch request response message to the target CU in response to the path switch request message in step 820.
  • the path switch request response message is used to indicate whether the path switch is successfully completed.
  • Step 823 after the path switching, the UPF can send the downlink data of the terminal device to the target CU instead of the source CU.
  • Step 824 after receiving the notification message #C, the target CU may also send a notification message #D to the target DU, or the target DU receives the notification message #D from the target CU.
  • the notification message #D includes at least one of the following information: the identity of the target cell, beam information or access information.
  • the identity of the target cell For the description of the beam information and access information, refer to step 815.
  • the target DU can complete the random access process with the terminal device based on the information in the notification message #D.
  • steps 810-817 may continue to be executed.
  • the method 800 may include step 825, ie, the target CU sends data to the target DU in advance.
  • the target CU in advance means that the terminal device may not have accessed the target cell of the target DU of the target CU at this time, but the target CU sends the data of the terminal device from the source CU or UPF to the target DU in advance.
  • the target CU after receiving the second notification message #C, the target CU can perform early data transmission.
  • the target DU can immediately send data to the terminal device, which is conducive to sending the data to the terminal device as soon as possible and avoiding data failure.
  • method 800 may include step 825 without limitation.
  • Step 826 The terminal device and the target DU perform the target cell access process.
  • step 826 may refer to existing standards and will not be described in detail.
  • the terminal device switches to the target cell using an access method based on random access-free.
  • the target cell may be configured with multiple carriers, for example, two carriers, NUL and SUL.
  • the terminal device and the target access network device need to have a consistent understanding to ensure that the cell switching can be successful.
  • Solution 1 In the configuration information of the candidate cells provided in step 804 and step 806, a candidate cell only provides the configuration of SUL or only provides the configuration of NUL. After the terminal device receives the handover command in step 808, it determines to use SUL or NUL to access/handover to the target cell according to the configuration of SUL or NUL provided by the target cell.
  • Solution 2 In the configuration information of the candidate cells provided in step 804 and step 806, a candidate cell provides the configuration of SUL and the configuration of NUL, and has an additional field for indicating whether SUL or NUL should be used.
  • the terminal device receives the handover command in step 808, it determines whether to use SUL or NUL for access/handover to the target cell according to the field of the target cell for indicating whether SUL or NUL should be used.
  • a candidate cell provides SUL configuration and NUL configuration, and notifies the source access network device (e.g., source CU and/or source DU) of the provision of SUL and NUL configurations, and the source access network device determines the uplink carrier that the target cell should use during a certain switching.
  • the source access network device determines to select a certain uplink carrier based on the channel measurement result fed back by the terminal device, and notifies the terminal device of the determined result through the switching command of step 808.
  • the terminal device selects SUL or NUL to access/switch to the target cell based on the carrier information indicated in the switching command (e.g., MAC CE).
  • the source access network device may notify the target access network device (e.g., target CU and/or target DU) of the selected carrier information through steps 809, 815, and 824.
  • a candidate cell provides the configuration and For the configuration of NUL, the source access network device (e.g., source CU and/or source DU) interacts with the target access network device (e.g., target CU and/or target DU) before sending the handover command of step 808.
  • the interactive process is not shown in the figure, such as sending a request message and receiving a response message.
  • the target access network device informs the source access network device which uplink carrier of the target cell should be selected, and the source access network device notifies the terminal device of the handover command in step 808.
  • the terminal device selects SUL or NUL to access/handover to the target cell according to the carrier information indicated in the handover command (e.g., MAC CE).
  • a candidate cell provides the configuration of SUL and the configuration of NUL.
  • the terminal device selects the uplink carrier of the target cell according to the channel quality of the target cell. For example, when the reference signal received power (RSRP) of the downlink reference signal of the target cell is less than a certain configured threshold value, the terminal device selects the SUL access of the target cell; otherwise, the NUL access of the target cell is selected.
  • RSRP reference signal received power
  • the target access network device e.g., the target CU and/or the target DU
  • the target access network device will attempt to receive the uplink signal sent by the terminal device on both SUL and NUL (e.g., the target access network device receives the uplink message on the pre-configured uplink authorization resources of SUL and NUL), or attempts to send a downlink signal to the terminal device on both SUL and NUL (e.g., the target access network device sends scheduling information to the terminal device on both SUL and NUL).
  • step 826 can be implemented in combination with the switching method of the embodiment of the present application, or can be implemented independently as a separate embodiment.
  • Step 827 after the terminal device successfully accesses the target cell of the target DU of the target CU, the target DU sends a switching success indication to the target CU to notify the target CU that the terminal device has successfully switched to the target cell.
  • Step 828 after receiving the switching success indication, the target CU sends the data from the terminal device of the source CU or UPF to the target DU.
  • Step 825 and step 828 are two implementations of the target CU sending data from the source CU or UPF to the target DU, and the two differ in the timing of sending the data.
  • Step 825 is executed after receiving the notification message #C
  • step 828 is executed after receiving the switching success indication, and either one can be executed.
  • Step 829 The target DU sends the received data to the terminal device.
  • method 800 may include step 830, that is, the target CU sends a notification message #E to the source CU, which is used to notify the source CU that the terminal device has successfully accessed the target cell, so that the source CU processes the configuration information and context information of the terminal device in the source cell.
  • the source CU may retain the configuration information and context information of the terminal device in the source cell so that the terminal device can continue to use the information after switching back.
  • Another possible implementation method is that after receiving the notification message #E, the source CU releases the configuration information and context information of the terminal device in the source cell.
  • method 800 may include step 831, that is, the source CU sends a notification message #F to the candidate CU, or the candidate CU receives a notification message #F from the source CU, wherein the notification message #F includes the association relationship between the candidate cell determined in step 805 and the channel information carried by the user plane of the candidate CU corresponding to the candidate cell.
  • the target CU learns of the association relationship, it can send a path switching request message to the AMF based on the association relationship when it subsequently acts as the source CU to instruct the terminal device to switch the cell.
  • the target CU that is switched for the first time acts as the source CU for subsequent switching, it is not necessary to re-execute steps 801 to 804 to obtain the association relationship between the candidate cell identity and the channel information carried by the user plane of the corresponding candidate CU, thereby reducing the signaling overhead and allowing the subsequent switching process and the corresponding path switching process to be executed faster.
  • This application does not limit the timing of executing step 831.
  • a possible implementation method, as shown in FIG8 is that the source CU may execute after step 830 , that is, the source CU sends a notification message #F to the candidate CU after learning that the terminal device has successfully accessed the target cell.
  • the source CU may execute after step 805 without waiting until the terminal device successfully accesses the target cell.
  • CU#1 is the source CU
  • CU#2 and CU#3 are candidate CUs
  • CU#1 has obtained the association relationship between the candidate cell identities of CU#2 and CU#3 and the channel information carried by the user plane of CU#2, as well as the association relationship between the candidate cell identity of CU#3 and the channel information carried by the user plane of CU#3.
  • CU#1 may send the obtained association relationship to CU#2 and CU#3, so that after the terminal device switches to CU#2 or CU#3, CU#2 or CU#3 can continue to initiate a path switching request to the AMF.
  • the computer program or instruction may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer program or instruction may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired or wireless means.
  • the computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server, data center, etc. that integrates one or more available media.
  • the available medium may be a magnetic medium, for example, a floppy disk, a hard disk, a tape; it may also be an optical medium, for example, a digital video disc; it may also be a semiconductor medium, for example, a solid-state hard disk.

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Abstract

本申请提供了一种切换方法和通信装置，可以根据用于指示终端设备将切换至的目标小区的通知消息来发起终端设备的用户面承载的切换，换句话说，终端设备的用户面承载的切换可以由该通知消息触发。相较于在接收到终端设备成功接入目标小区的指示后再发起终端设备的用户面承载的切换，可以更早的执行终端设备的用户面承载的切换。而在执行终端设备的用户面承载的切换后，终端设备的业务数据可以直接发送给目标接入网设备，无需再经过源接入网设备的转发。因此可以减少经由源接入网设备到目标接入网设备的数据转发过程的数据，从而减少失效的数据，进而提升业务体验。

Description

一种切换方法和通信装置
本申请要求于2023年6月15日提交中国国家知识产权局、申请号为202310718509.9、申请名称为“一种切换方法和通信装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，更具体地，涉及一种切换方法和通信装置。
背景技术
在移动通信系统中，终端设备的位置移动可能会导致终端设备与网络设备之间的通信链路发生变化，网络设备会根据终端设备的移动情况指示终端设备进行小区切换。
在切换过程中，存在下行数据从源接入网设备转发给目标接入网设备，再由目标接入网设备将数据发送给终端设备的过程。数据由源接入网设备转发给目标接入网设备的这段过程会带来时延，这段时延可能导致数据到达终端设备时已失效，影响业务体验。
发明内容
本申请提供了一种切换方法和通信装置，能够减少经过数据转发的数据，从而减少失效的数据，进而提升业务体验。
第一方面，提供了一种切换方法，所述方法可以由源集中式单元(central unit，CU)执行，也可以由源CU中的模块或单元(如芯片或电路)执行，下文统一使用源CU进行描述。
所述方法包括：源CU接收来自源分布式单元(distributed unit，DU)的第一通知消息，所述第一通知消息用于指示终端设备将切换至的目标小区，所述目标小区为目标CU下的目标DU的小区；所述源CU根据所述第一通知消息，向核心网设备发送第一请求消息，所述第一请求消息用于请求将所述终端设备的用户面承载切换至所述目标CU。
基于上述方法，源CU可以根据用于指示终端设备将切换至的目标小区的第一通知消息来发起终端设备的用户面承载的切换，换句话说，终端设备的用户面承载的切换可以由第一通知消息触发。相较于在接收到终端设备成功接入目标小区的指示后再发起终端设备的用户面承载的切换，上述方法可以更早的执行终端设备的用户面承载的切换。而在执行终端设备的用户面承载的切换后，终端设备的业务数据可以直接发送给目标CU，无需再经过源CU向目标CU的数据转发过程。因此，上述方法可以减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，进而提升业务体验。
结合第一方面，在一种可能的实现方式中，所述第一通知消息包括所述目标小区的第一标识；所述源CU根据所述第一通知消息，向核心网设备发送第一请求消息，包括：所述源CU根据所述第一标识、以及第一关联关系，向所述核心网设备发送所述第一请求消息，所述第一关联关系用于指示所述第一标识与第一信息的关联关系，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第一请求消息包括所述第一信息。
基于上述方法，源CU可以根据目标小区的第一标识与用于指示目标CU的用户面承载的通道信息的第一关联关系获取目标CU的用户面承载的通道信息，从而可以向核心网设备提供目标CU的用户面承载的通道信息，进而实现由源CU发起终端设备的用户面承载的切换。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，在所述源CU接收到所述第一通知消息之前，所述方法还包括：所述源CU向所述目标CU发送第二请求消息，所述第二请求消息用于请求所述第一信息；所述源CU接收来自所述目标CU的第二响应消息，所述第二响应消息包括所述目标小区的第二标识和所述第一信息；所述源CU根据所述第二标识和所述第一信息，确定所述第一关联关系。
基于上述方法，可以实现在源CU向核心网设备发送第一请求消息之前为源CU预配置第一关联关系，这样可以降低发起终端设备的用户面承载的切换的时延。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第一通知消息包括所述目标小 区的第一标识；所述源CU根据所述第一通知消息，向核心网设备发送第一请求消息，包括：所述源CU根据所述第一标识，确定所述目标小区所属的所述目标CU的标识；所述源CU根据所述目标CU的标识、以及第二关联关系，向所述核心网设备发送所述第一请求消息，所述第二关联关系用于指示所述目标CU的标识与第一信息的关联关系，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第一请求消息包括所述第一信息。
基于上述方法，源CU可以根据目标小区的第一标识、目标CU与用于指示目标CU的用户面承载的通道信息的第二关联关系，获取目标CU的用户面承载的通道信息，从而可以向核心网设备提供目标CU的用户面承载的通道信息，进而实现由源CU发起终端设备的用户面承载的切换。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，在所述源CU根据所述第一通知消息，向核心网设备发送第一请求消息之前，所述方法还包括：所述源CU向所述目标CU发送第二请求消息，所述第二请求消息用于请求所述第一信息；所述源CU接收来自所述目标CU的第二响应消息，所述第二响应消息包括所述目标CU的标识和所述第一信息；所述源CU根据所述目标CU的标识和所述第一信息，确定所述第二关联关系。
基于上述方法，可以实现在源CU向核心网设备发送第一请求消息之前为源CU预配置第二关联关系，这样可以降低发起终端设备的用户面承载的切换的时延。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第二请求消息还包括第二信息，所述第二信息用于请求由源CU发起路径切换；所述第二响应消息还包括第三信息，所述第三信息用于指示允许由所述源CU发起路径切换。
基于上述方法，可以实现源CU于目标CU协商确定由源CU发起终端设备的用户面承载的切换，有助于由更合适的CU发起终端设备的用户面承载的切换。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第二请求消息还包括第四信息，所述第四信息用于指示由源CU发起路径切换。
换句话说，源CU确定发起终端设备的用户面承载的切换时通知目标CU即可，无需目标CU的确认或许可。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU向候选CU发送至少一个关联关系，所述候选CU包括所述目标CU，所述至少一个关联关系包括所述第一关联关系。
基于此，目标CU在作为后续切换的源CU时，可以不需要重新获得候选小区与对应的候选CU的用户面承载的通道信息的关联关系，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第一信息包括以下信息中的至少一个：所述目标CU的用户面承载的下行终结点的互联网协议(Internet Protocol，IP)地址、或所述目标CU的用户面承载的下行终结点的GPRS隧道协议-隧道端点标识(GPRS tunneling protocol–tunnel endpoint identifier，GTP-TEID)。其中，GPRS为通用分组无线系统(general packet radio system)。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU根据所述第一通知消息，向所述目标CU转发所述终端设备的业务数据。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU向所述目标CU发送第二通知消息，所述第二通知消息用于指示所述终端设备将切换至的所述目标小区。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第二通知消息包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端设备通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU向所述目标CU发送所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
基于上述方法，在空口和网络侧可以使用不同的小区标识，这样有助于可以避免在空口暴露小区的真实身份信息，使得通信系统更为安全。并且，考虑到目标小区的第一标识是源CU确定的，目标CU并不知道，通过上述方法可以使得目标CU获知目标小区的第一标识与目标小区的第二标识的对应关系。这 样，包括源CU和目标CU在与终端通信时，可以使用相同的候选小区的第一标识，可以避免重复配置终端设备。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述第一标识的长度小于所述第二标识的长度。这样，可以减少空口的信令开销。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU接收来自所述核心网设备的第一响应消息，所述第一响应消息用于指示路径切换成功。
结合第一方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU接收来自所述目标CU的第五通知消息，所述第五通知消息用于指示所述终端设备已经成功接入所述目标小区。
第二方面，提供了一种切换方法，所述方法可以由目标CU执行，也可以由目标CU中的模块或单元(如芯片或电路)执行，下文统一使用目标CU进行描述。
第二方面或其实现方式中与第一方面或其实现方式中相同的术语或特征，可以参考第一方面或其实现方式，其技术效果可参照第一方面或其实现方式中的技术效果。
所述方法包括：所述目标CU接收来自源CU的第二请求消息，所述第二请求消息用于请求第一信息，所述第一信息用于指示所述目标CU的用户面承载的通道信息；所述目标CU向所述源CU发送第二响应消息，所述第二响应消息包括目标小区的第二标识和所述第一信息，所述目标小区为所述目标CU下的目标分布式单元DU的小区。
结合第二方面，在一种可能的实现方式中，所述第二请求消息还包括第二信息，所述第二信息用于请求由所述源CU发起路径切换；所述第二响应消息还包括第三信息，所述第三信息用于指示允许由所述源CU发起路径切换。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述第二请求消息还包括第四信息，所述第四信息用于指示由所述源CU发起路径切换。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的至少一个关联关系，所述至少一个关联关系包括第一关联关系，所述第一关联关系用于指示所述目标小区的第一标识与所述第一信息的关联关系。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的所述终端设备的业务数据；所述目标CU向所述目标DU发送所述业务数据；所述目标CU在向所述目标DU发送所述业务数据之后，接收来自所述目标DU的第四通知消息，所述第四通知消息用于指示所述终端设备已经成功接入所述目标小区。
基于上述方法，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU可以立即向终端设备发送数据，从而有利于尽早将数据发送给终端设备，避免数据失效。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU向所述源CU发送第五通知消息，所述第五通知消息用于指示所述终端设备已经成功接入所述目标小区。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的第二通知消息，所述第二通知消息用于指示所述终端设备将切换至的所述目标小区。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述第二通知消息包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端设备通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU根据所述第二通知消息，向目标DU发送第六通知消息，所述第六通知消息包括以下信息中的至少一个：所述目标小区的第一标识、所述波束信息、或所述接入信息。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述第二通知消息包括第七信息，所述第七信息用于指示所述源CU已经发起了路径切换；所述方法还包括：所述目标CU根据所述第七信息，不执行路径切换。
结合第二方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
第三方面，提供了一种切换方法，所述方法可以由目标CU执行，也可以由目标CU中的模块或单元 (如芯片或电路)执行，下文统一使用目标CU进行描述。
所述方法包括：目标CU接收来自源CU的第一通知消息，所述第一通知消息用于指示终端设备将切换至的目标小区，所述目标小区为所述目标CU下的目标DU的小区；所述目标CU根据所述第一通知消息，向核心网设备发送第一请求消息，所述第一请求消息用于请求将所述终端设备的用户面承载切换至所述目标CU。
基于上述方法，目标CU可以根据用于指示终端设备将切换至的目标小区的第一通知消息来发起终端设备的用户面承载的切换，换句话说，终端设备的用户面承载的切换可以由第一通知消息触发。相较于在接收到终端设备成功接入目标小区的指示后再发起终端设备的用户面承载的切换，上述方法可以更早的执行终端设备的用户面承载的切换。而在执行终端设备的用户面承载的切换后，终端设备的业务数据可以直接发送给目标CU，无需再经过源CU向目标CU的数据转发过程。因此，上述方法可以减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，进而提升业务体验。
结合第三方面，在一种可能的实现方式中，所述第一通知消息包括第五信息，所述第五信息用于指示所述源CU未发起路径切换。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，在接收来自源CU的所述第一通知消息之前，所述方法还包括：所述目标CU接收来自所述源CU的第二请求消息，所述第二请求消息用于请求第一信息，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第二请求消息还包括第二信息，所述第二信息用于请求由所述源CU发起路径切换；所述目标CU向所述源CU发送第二响应消息，所述第二响应消息包括第六信息，所述第六信息用于指示不允许由所述源CU发起路径切换。
基于上述方法，可以实现源CU于目标CU协商确定由源CU发起终端设备的用户面承载的切换，有助于由更合适的CU发起终端设备的用户面承载的切换。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述第一信息包括以下信息中的至少一个：所述目标CU对应的用户面承载的下行终结点的IP地址、或所述目标CU对应的用户面承载的下行终结点的GTP-TEID。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述第一通知消息包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端设备通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU根据所述第一通知消息，向所述目标DU发送第三通知消息，所述第三通知消息包括以下信息中的至少一个：所述第一标识、所述波束信息、或所述接入信息。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的至少一个关联关系，所述关联关系用于指示候选小区的标识和所述候选小区对应的候选CU的用户面承载的通道信息的关联关系。
基于此，目标CU在作为后续切换的源CU时，可以不需要重新获得候选小区与对应的候选CU的用户面承载的通道信息的关联关系，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的所述终端设备的业务数据；所述目标CU向所述目标DU发送所述业务数据；在向所述目标DU发送所述业务数据之后，所述目标CU接收来自所述目标DU的第四通知消息，所述第四通知消息用于指示所述终端设备已经成功接入所述目标小区。
基于上述方法，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU可以立即向终端设备发送数据，从而有利于尽早将数据发送给终端设备，避免数据失效。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自所述源CU的所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
基于上述方法，在空口和网络侧可以使用不同的小区标识，这样有助于可以避免在空口暴露小区的真实身份信息，使得通信系统更为安全。并且，考虑到目标小区的第一标识是源CU确定的，目标CU并不知道，通过上述方法可以使得目标CU获知目标小区的第一标识与目标小区的第二标识的对应关系。这 样，包括源CU和目标CU在与终端通信时，可以使用相同的候选小区的第一标识，可以避免重复配置终端设备。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述第一标识的长度小于所述第二标识的长度。这样，可以减少空口的信令开销。
结合第三方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述目标CU接收来自核心网设备的第一响应消息，所述第一响应消息用于指示路径切换成功。
第四方面，提供了一种切换方法，所述方法可以由源CU执行，也可以由源CU中的模块或单元(如芯片或电路)执行，下文统一使用源CU进行描述。
第四方面或其实现方式中与第三方面或其实现方式中相同的术语或特征，可以参考第三方面或其实现方式，其技术效果可参照第三方面或其实现方式中的技术效果。
所述方法包括：源CU接收来自源DU的第八通知消息，所述第八通知消息用于指示终端设备将切换至的目标小区，所述目标小区为目标CU下的目标DU的小区；所述源CU根据所述第八通知消息，向所述目标CU发送第一通知消息，所述第一通知消息用于指示所述终端设备将切换至的所述目标小区。
结合第四方面，在一种可能的实现方式中，所述第一通知消息包括第五信息，所述第五信息用于指示所述源CU未发起路径切换。
结合第四方面或其任意实现方式，在另一种可能的实现方式中，在所述源CU根据所述第八通知消息，向所述目标CU发送第一通知消息之前，所述方法还包括：所述源CU向所述目标CU发送第二请求消息，所述第二请求消息用于请求第一信息，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第二请求消息还包括第二信息，所述第二信息用于请求由所述源CU发起路径切换；所述源CU接收来自所述目标CU的第二响应消息，所述第二响应消息包括第六信息，所述第六信息用于指示不允许由所述源CU发起路径切换。
结合第四方面或其任意实现方式，在另一种可能的实现方式中，所述第一通知消息还包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
结合第四方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU向候选CU发送至少一个关联关系，所述候选CU包括所述目标CU，所述关联关系用于指示候选小区的标识和所述候选小区对应的候选CU的用户面承载的通道信息的关联关系。
结合第四方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU根据所述第八通知消息，向所述目标CU转发所述终端设备的业务数据。
结合第四方面或其任意实现方式，在另一种可能的实现方式中，所述方法还包括：所述源CU向所述目标CU发送所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
第五方面，提供了一种切换方法，所述方法可以由目标接入网设备执行，也可以由目标接入网设备中的模块或单元(如芯片或电路)执行，下文统一使用目标接入网设备进行描述。
所述方法包括：目标接入网设备确定目标小区的配置信息，所述目标小区的配置信息包括第一载波的配置信息，所述第一载波为普通上行(normal uplink，NUL)载波或辅助上行(supplementary uplink，SUL)载波；所述目标接入网设备向终端设备发送所述目标小区的配置信息。
一种可能的实现方式，目标接入网设备通过源接入网设备向终端设备发送目标小区的配置信息。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由目标接入网设备确定使用NUL还是SUL完成目标小区的切换过程，并向终端设备提供相应的载波的配置信息，以便终端设备使用该载波的配置信息切换至目标小区，有助于保证小区切换的成功进行。
第六方面，提供了一种切换方法，所述方法可以由终端设备执行，也可以由终端设备中的模块或单元(如芯片或电路)执行，下文统一使用终端设备进行描述。
所述方法包括：终端设备接收来自目标接入网设备的目标小区的配置信息，所述目标小区的配置信息包括第一载波的配置信息，所述第一载波为NUL载波或SUL载波；所述终端设备接收来自源接入网设备的切换命令，所述切换命令用于指示切换至所述目标小区；所述终端设备根据所述目标小区的配置信息，使用所述第一载波进行向所述目标小区的切换过程。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由目标接入网设备确定使用NUL还是SUL完成目标小区的切换过程，并向终端设备提供相应的载波的配置信息，终端设备可以使用该载波的配置信息切换至目标小区，有助于保证小区切换的成功进行。
第七方面，提供了一种切换方法，所述方法可以由目标接入网设备执行，也可以由目标接入网设备中的模块或单元(如芯片或电路)执行，下文统一使用目标接入网设备进行描述。
所述方法包括：目标接入网设备确定目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息、SUL载波的配置信息、以及载波信息，所述载波信息用于指示使用所述NUL载波完成目标小区的切换过程，或者所述载波信息用于指示使用所述SUL载波完成所述目标小区的切换过程；所述目标接入网设备向终端设备发送所述目标小区的配置信息。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由目标接入网设备确定使用NUL还是SUL完成针对目标小区的切换过程，并指示给终端设备，有助于保证小区切换的成功进行。
第八方面，提供了一种切换方法，所述方法可以由终端设备执行，也可以由终端设备中的模块或单元(如芯片或电路)执行，下文统一使用终端设备进行描述。
所述方法包括：终端设备接收来自目标接入网设备的目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息、SUL载波的配置信息、以及载波信息，所述载波信息用于指示使用第一载波完成目标小区的切换过程，所述第一载波为所述NUL载波或者所述SUL载波；所述终端设备接收来自源接入网设备的切换命令，所述切换命令用于指示切换至所述目标小区；所述终端设备根据所述载波信息，使用所述第一载波进行向所述目标小区的切换过程。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由目标接入网设备确定使用NUL还是SUL完成针对目标小区的切换过程，并指示给终端设备，有助于保证小区切换的成功进行。
第九方面，提供了一种切换方法，所述方法可以由目标接入网设备执行，也可以由目标接入网设备中的模块或单元(如芯片或电路)执行，下文统一使用目标接入网设备进行描述。
所述方法包括：目标接入网设备向终端设备发送目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息和SUL载波的配置信息；所述目标接入网设备向源接入网设备发送第一消息，所述第一消息用于通知向所述终端设备提供了所述NUL载波的配置信息和所述SUL载波的配置信息。
基于上述方法，在目标小区有NUL和SUL两个载波时，目标接入网设备可以向终端设备提供目标小区的NUL载波的配置信息和SUL载波的配置信息，并将向终端设备提供了的目标小区的NUL载波的配置信息和SUL载波的配置信息的情况告知源接入网设备，以便由源接入网设备确定使用NUL还是SUL完成目标小区的切换过程，有助于保证小区切换的成功进行。
第十方面，提供了一种切换方法，所述方法可以由源接入网设备执行，也可以由源接入网设备中的模块或单元(如芯片或电路)执行，下文统一使用源接入网设备进行描述。
所述方法包括：源接入网设备接收来自目标接入网设备的第一消息，所述第一消息用于通知向终端设备提供了目标小区的NUL载波的配置信息和SUL载波的配置信息；所述源接入网设备确定使用第一载波完成所述目标小区的切换过程；所述源接入网设备向所述终端设备发送切换命令，所述切换命令用于指示切换至所述目标小区，所述切换命令包括载波信息，所述载波信息用于指示使用所述第一载波完成目标小区的切换过程，所述第一载波为所述NUL载波或者所述SUL载波。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由源接入网设备确定使用NUL还是SUL完成针对目标小区的切换过程，并通过切换命令指示给终端设备，有助于保证小区切换的成功进行。
第十一方面，提供了一种切换方法，所述方法可以由目标接入网设备执行，也可以由目标接入网设备中的模块或单元(如芯片或电路)执行，下文统一使用目标接入网设备进行描述。
所述方法包括：目标接入网设备向终端设备发送目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息和SUL载波的配置信息；所述目标接入网设备向源接入网设备发送载波信息，所述载波信息用于指示使用第一载波完成目标小区的切换过程，所述第一载波为所述NUL载波或者所述SUL载波。
基于上述方法，在目标小区有NUL和SUL两个载波时，目标接入网设备可以向终端设备提供目标小区的NUL载波的配置信息和SUL载波的配置信息，并告知源接入网设备使用NUL载波还是SUL载波完成目标小区的切换过程，有助于保证小区切换的成功进行。
第十二方面，提供了一种切换方法，所述方法可以由源接入网设备执行，也可以由源接入网设备中 的模块或单元(如芯片或电路)执行，下文统一使用源接入网设备进行描述。
所述方法包括：源接入网设备接收来自目标接入网设备的载波信息，所述载波信息用于指示使用第一载波完成目标小区的切换过程，所述第一载波为所述目标小区的NUL载波或者所述目标小区的SUL载波；所述源接入网设备向所述终端设备发送切换命令，所述切换命令用于指示切换至所述目标小区，所述切换命令包括所述载波信息。
基于上述方法，在目标小区有NUL和SUL两个载波时，目标接入网设备可以向终端设备提供目标小区的NUL载波的配置信息和SUL载波的配置信息，并告知源接入网设备使用NUL载波还是SUL载波完成目标小区的切换过程，源接入网设备可以通过切换命令指示给终端设备使用NUL载波还是SUL载波完成目标小区的切换过程，有助于保证小区切换的成功进行。
第十三方面，提供了一种切换方法，所述方法可以由终端设备执行，也可以由终端设备中的模块或单元(如芯片或电路)执行，下文统一使用终端设备进行描述。
所述方法包括：终端设备接收来自目标接入网设备的目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息和SUL载波的配置信息；所述终端设备接收来自源接入网设备的切换命令，所述切换命令用于指示切换至所述目标小区，所述切换命令包括载波信息，所述载波信息用于指示使用第一载波完成目标小区的切换过程，所述第一载波为所述NUL载波或者所述SUL载波；所述终端设备根据所述载波信息，使用所述第一载波进行向所述目标小区的切换过程。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由源接入网设备可以通过切花命令指示使用NUL还是SUL完成针对目标小区的切换过程，有助于保证小区切换的成功进行。
第十四方面，提供了一种切换方法，所述方法可以由终端设备执行，也可以由终端设备中的模块或单元(如芯片或电路)执行，下文统一使用终端设备进行描述。
所述方法包括：终端设备接收来自目标接入网设备的目标小区的配置信息，所述目标小区的配置信息包括NUL载波的配置信息和SUL载波的配置信息；所述终端设备接收来自源接入网设备的切换命令，所述切换命令用于指示切换至所述目标小区；所述终端设备根据所述目标小区的信道质量，确定使用第一载波完成所述目标小区的切换过程，所述第一载波为所述NUL载波或者所述SUL载波；所述终端设备使用所述第一载波进行向所述目标小区的切换过程。
基于上述方法，在目标小区有NUL和SUL两个载波时，可以由终端设备确定使用NUL还是SUL完成针对目标小区的切换过程，有助于保证小区切换的成功进行。
结合第十四方面，在一种可能的实现方式中，所述终端设备根据所述目标小区的信道质量，确定使用第一载波完成所述目标小区的切换过程，包括：所述终端设备根据所述目标小区的信道质量、以及预设门限值，确定使用第一载波完成所述目标小区的切换过程。
一种可能的实现方式，当目标小区的信道质量小于预设门限值时，终端设备确定使用目标小区的SUL载波进行向目标小区的切换过程，否则终端设备确定使用目标小区的NUL载波进行向目标小区的切换过程。
例如，当目标小区的下行参考信号的参考信号接收功率小于预设的功率门限值时，终端设备确定使用目标小区的SUL载波进行向目标小区的切换过程，否则终端设备确定使用目标小区的NUL载波进行向目标小区的切换过程。
第十五方面，提供了一种通信装置，该装置用于执行上述任意一方面或其实现方式提供的方法。具体地，该装置可以包括用于执行上述任意一方面或其实现方式提供的方法的单元和/或模块，如处理单元和/或通信单元。
在一种实现方式中，该装置为源CU、目标CU、源接入网设备、目标接入网设备或终端设备。当该装置为源CU、目标CU、源接入网设备、目标接入网设备或终端设备时，通信单元可以是收发器，或，输入/输出接口，或者通信接口；处理单元可以是至少一个处理器。可选地，收发器为收发电路。可选地，输入/输出接口为输入/输出电路。
在另一种实现方式中，该装置为用于源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的芯片、芯片系统或电路。当该装置为用于源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的芯片、芯片系统或电路时，通信单元可以是该芯片、芯片系统或电路上的输入/输出接口、接口电路、输出电路、输入电路、管脚或相关电路等；处理单元可以是至少一个处理器、处理电路或逻辑电路等。
第十六方面，提供了一种通信装置，该装置包括：存储器，用于存储程序；至少一个处理器，用于执行存储器存储的计算机程序或指令，以执行上述任意一方面或其实现方式提供的方法。
在一种实现方式中，该装置为源CU、目标CU、源接入网设备、目标接入网设备或终端设备。
在另一种实现方式中，该装置为用于源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的芯片、芯片系统或电路。
第十七方面，提供了一种通信装置，该装置包括：至少一个处理器和通信接口，该至少一个处理器用于通过该通信接口获取存储在存储器的计算机程序或指令，以执行上述任意一方面或其实现方式提供的方法。该通信接口可以由硬件或软件实现。
在一种实现方式中，该装置还包括该存储器。
第十八方面，提供了一种处理器，用于执行上述各方面提供的方法。
对于处理器所涉及的发送和获取/接收等操作，如果没有特殊说明，或者，如果未与其在相关描述中的实际作用或者内在逻辑相抵触，那么可以理解为处理器输出和接收、输入等操作，也可以理解为由射频电路和天线所进行的发送和接收操作，本申请对此不做限定。
第十九方面，提供了一种计算机可读存储介质，该计算机可读介质存储用于设备执行的程序代码，该程序代码包括用于执行上述任意一方面或其实现方式提供的方法。
第二十方面，提供了一种包含指令的计算机程序产品，当该计算机程序产品在计算机上运行时，使得计算机执行上述任意一方面或其实现方式提供的方法。
第二十一方面，提供了一种芯片，芯片包括处理器与通信接口，处理器通过通信接口读取存储器上存储的指令，执行上述任意一方面或其实现方式提供的方法。该通信接口可以由硬件或软件实现。
可选地，作为一种实现方式，芯片还包括存储器，存储器中存储有计算机程序或指令，处理器用于执行存储器上存储的计算机程序或指令，当计算机程序或指令被执行时，处理器用于执行上述任意一方面或其实现方式提供的方法。
其中，当本申请提供的方法由芯片执行时，本申请不限定具体实现本申请方法的芯片个数，例如可以由一个芯片执行，也可以是2个或2个以上的芯片执行。并且，当实现本申请方法的芯片个数为2个及2个以上时，不限定芯片厂家，可以是相同厂家，也可以是不同厂家。
第二十二方面，提供了一种通信系统，包括上文所述的源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的至少一个。
第二十三方面，提供了一种计算机程序，当其在计算机上运行时，使得上述任意一方面或其实现方式提供的方法被执行。
附图说明
图1是适用本申请的实施例的一个网络架构图。
图2是CU-DU架构的一个示意图。
图3是同一个CU下不同DU之间的L1/L2触发的移动性(L1/L2 Triggered Mobility,LTM)切换的示意性流程图。
图4是跨基站的小区切换的示意性流程图。
图5是本申请提供的切换方法500的示意性流程图。
图6是本申请提供的切换方法600的示意性流程图。
图7是本申请提供的切换方法700的示意性流程图。
图8是本申请提供的切换方法800的示意性流程图。
图9是本申请提供的切换方法900的示意性流程图。
图10是本申请提供的切换方法1000的示意性流程图。
图11是本申请提供的通信装置的一种结构示意图。
图12是本申请提供的通信装置的另一种结构示意图。
具体实施方式
为便于理解本申请的实施例，在介绍本申请的实施例之前，先做出以下几点说明。
“用于指示”或“指示”可以包括用于直接指示和用于间接指示，或者说“用于指示”或“指示” 可以显式地和/或隐式地指示。第一、第二、等各种数字编号仅为描述方便进行的区分，并不用来限制本申请实施例的范围，例如区分不同的消息、不同的信息等。“预先定义”可以通过在设备中预先保存相应的代码、表格或其他可用于指示相关信息的方式来实现，本申请对于其具体的实现方式不做限定。涉及的“协议”可以是指通信领域的标准协议，例如可以包括长期演进(long term evolution，LTE)协议、新无线(new radio，NR)协议以及应用于未来的通信系统中的相关协议，本申请对此不做限定。“示例的”、“例如”、“示例性地”、“作为(另)一个示例”等词用于表示作例子、例证或说明。本申请中被描述为“示例”的任何实施例或设计方案不应被解释为比其它实施例或设计方案更优选或更具优势。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a、b和c中的至少一项(个)，可以表示：a，或，b，或，c，或，a和b，或，a和c，或，b和c，或，a、b和c。其中a、b和c分别可以是单个，也可以是多个。涉及网元A向网元B发送消息、信息或数据，以及网元B接收来自网元A的消息、信息或数据的相关描述，旨在说明该消息、信息或数据是要发给哪个网元，而并不限定它们之间是直接发送还是经由其他网元间接发送。“当……时”、“在……的情况下”、“若”以及“如果”等描述均指在某种客观情况下设备会做出相应的处理，并非是限定时间，且也不要求设备在实现时一定要有判断的动作，也不意味着存在其它限定。
此外，本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
下面对可以应用本申请的实施例的通信系统进行描述。
本申请的实施例可以应用于各种通信系统，例如：LTE系统、频分双工(frequency division duplex，FDD)系统、时分双工(time division duplex，TDD)系统、通用移动通信系统(universal mobile telecommunication system，UMTS)、全球互联微波接入(worldwide interoperability for microwave access，WiMAX)通信系统、第五代(5th generation，5G)系统或NR系统、第六代(6th generation，6G)系统或未来的通信系统等。本申请中所述的5G移动通信系统包括非独立组网(non-standalone，NSA)的5G移动通信系统或独立组网(standalone，SA)的5G移动通信系统。通信系统还可以是公共陆地移动通信网(public land mobile network，PLMN)网络、设备到设备(device-to-device，D2D)通信系统、机器到机器(machine to machine，M2M)通信系统、物联网(internet of Things，IoT)通信系统、车联万物(vehicle to everything，V2X)通信系统、无人机(uncrewed aerial vehicle，UAV)通信系统或者其他通信系统。
示例性地，图1示出了适用本申请的实施例的一个网络架构图。如图1所示，该网络架构具体可以包括三部分，分别是终端设备部分、数据网络(data network，DN)和运营商网络部分。下面对各部分的网元的功能进行简单说明。
终端设备部分可以包括终端设备。终端设备也可称为用户设备(user equipment，UE)、接入终端、终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、用户代理或用户装置等，是一种具有无线收发功能的设备，可以经无线接入网(radio access network，RAN)中的接入网设备(或者也可以称为接入设备)与一个或多个核心网(core network，CN)设备进行通信。终端设备可以部署在陆地上，包括室内或室外、手持或车载；也可以部署在水面上(例如轮船等)；还可以部署在空中(例如飞机、气球和卫星上等)。终端设备可以是蜂窝电话(cellular phone)、无绳电话、会话启动协议(session initiation protocol，SIP)电话、智能电话(smart phone)、手机(mobile phone)、无线本地环路(wireless local loop，WLL)站、个人数字处理(personal digital assistant，PDA)等。或者，终端设备还可以是具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它设备、车载设备、可穿戴设备、无人机设备或物联网、车联网中的终端、5G网络以及未来网络中的任意形态的终端、中继用户设备或者未来演进的6G网络中的终端等。终端设备还可以是虚拟现实(virtual reality，VR)终端、增强现实(augmented reality，AR)终端、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无 线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等。本申请的实施例对终端设备所采用的具体技术和具体设备形态不做限定。
数据网络，也可以称为分组数据网络(packet data network，PDN)，通常是位于运营商网络之外的网络，例如第三方网络。当然，在一些实现方式中，DN也可以由运营商进行部署，即DN属于PLMN中的一部分。运营商网络可以接入多个数据网络DN，数据网络DN上可部署多种业务，可为终端设备提供数据和/或语音等服务。终端设备还可通过运营商网络访问数据网络DN，使用数据网络DN上部署的运营商业务，和/或第三方提供的业务。
运营商网络部分包括但不限于(无线)接入网((radio)access network，(R)AN)部分和核心网(core network，CN)部分。
(R)AN可以看作是运营商网络的子网络，是运营商网络中业务节点与终端设备之间的实施系统。终端设备要接入运营商网络，首先是经过(R)AN，进而可通过(R)AN与运营商网络的业务节点连接。本申请实施例中的接入网设备(RAN设备)，是一种为终端设备提供无线通信功能的设备。本申请的实施例对接入网设备所采用的具体技术和具体设备形态不做限定。
在一种可能的场景中，接入网设备可以是基站(base station)、演进型基站(evolved NodeB，eNodeB)、接入点(access point，AP)、发送接收点(transmission reception point，TRP)、下一代基站(next generation NodeB，gNB)、第六代(6th generation，6G)移动通信系统中的下一代基站、无线高保真(wireless fidelity，WiFi)系统中的接入节点或未来移动通信系统中的基站中的接入节点等。接入网设备可以是宏基站、微基站或室内站、中继节点或施主节点、或者是CRAN场景下的无线控制器。可选的，接入网设备还可以是服务器，可穿戴设备，车辆或车载设备等。例如，车辆外联(vehicle to everything，V2X)技术中的接入网设备可以为路侧单元(road side unit，RSU)。
在另一种可能的场景中，由多个接入网设备协作协助终端设备实现无线接入，不同接入网设备分别实现基站的部分功能。例如，接入网设备可以是CU，DU，CU-控制面(control plane，CP)，CU-用户面(user plane，UP)，或者无线单元(radio unit，RU)等。CU和DU可以是单独设置，或者也可以包括在同一个网元中，例如基带单元(baseband unit，BBU)中。RU可以包括在射频设备或者射频单元中，例如包括在射频拉远单元(remote radio unit，RRU)、有源天线处理单元(active antenna unit，AAU)或远程射频头(remote radio head，RRH)中。
在不同系统中，CU(或CU-CP和CU-UP)、DU或RU也可以有不同的名称，但是本领域的技术人员可以理解其含义。例如，在ORAN系统中，CU也可以称为O-CU(开放式CU)，DU也可以称为O-DU，CU-CP也可以称为O-CU-CP，CU-UP也可以称为O-CU-UP，RU也可以称为O-RU。为描述方便，本申请中以CU，CU-CP，CU-UP、DU和RU为例进行描述。本申请中的CU(或CU-CP、CU-UP)、DU和RU中的任一单元，可以是通过软件模块、硬件模块、或者软件模块与硬件模块结合来实现。
CN部分包括但不限于如下网络功能(Network Function，NF)：用户面功能(user plane function，UPF)、网络开放功能(network exposure function，NEF)、网络功能存储库功能(network function repository function，NRF)、策略控制功能(policy control function，PCF)、UDM、UDR、接入与移动性管理功能(access and mobility management function，AMF)、会话管理功能(session management function，SMF)和应用功能(application function，AF)。
下面对CN包含的NF功能进行进一步简要说明。
1、UPF是运营商网络与数据网络DN通信的网关，主要提供用户报文的转发、处理、与DN的连接、会话锚点、服务质量(quality of service，QoS)策略执行等用户面功能。
2、NEF是控制面功能，主要用于安全地向外部(如AF)开放由3GPP网络功能提供的业务和能力。NEF还允许经过认证和授权的应用功能在3GPP网络中安全地提供信息。
3、NRF是控制面功能，可用于维护网络中网络功能、服务的实时信息。
4、PCF是控制面功能，它支持统一的策略框架来治理网络行为、向其他控制功能提供策略规则、策略决策相关的签约信息等。
5、UDM是控制面功能，主要负责存储运营商网络中签约用户的签约数据。
6、UDR是控制面功能，主要负责数据存储和获取，例如为UDM提供存储和获取签约数据的功能、为PCF提供存储和获取策略数据、存储和获取用户的NF群组ID(group ID)信息等。
7、AMF是控制面功能，主要负责终端设备接入运营商网络的接入控制和移动性管理，例如包括移动状态管理，分配用户临时身份标识，认证和授权用户等功能。
8、SMF是控制面功能，主要负责会话管理(例如会话建立、修改和释放)、UPF网络功能的选择和控制、业务和会话连续性(service and session continuity，SSC)模式选择、漫游等会话相关的功能。
9、AF是控制面功能，用于提供应用层信息。
图1中Nnef、Nnrf、Npcf、Nudm、Nudr、Namf、Nsmf、N1、N2、N3、N4、N6以及N9为接口序列号。示例性的，上述接口序列号的含义可参见3GPP标准协议中定义的含义，本申请对于上述接口序列号的含义不做限制。需要说明的是，图1中的各个网络功能之间的接口名称仅仅是一个示例，在具体实现中，该系统架构的接口名称还可能为其他名称，本申请对此不作限定。各网元之间的接口可以是点对点接口，也可以是服务化接口，本申请不予限制。
应理解，上述所示的网络架构仅是示例性说明，适用本申请实施例的网络架构并不局限于此，任何能够实现上述各个网元的功能的网络架构都适用于本申请实施例。
还应理解，图1中所示的AMF、SMF、UPF、PCF、UDM、UDR、NEF、NRF、AF等功能或者网元，可以理解为用于实现不同功能的网元，例如可以按需组合成网络切片。这些网元可以各自独立的设备，也可以集成于同一设备中实现不同的功能，或者可以是硬件设备中的网络元件，也可以是在专用硬件上运行的软件功能，或者是平台(例如，云平台)上实例化的虚拟化功能，本申请对于上述网元的具体形态不作限定。
还应理解，上述命名仅为便于区分不同的功能而定义，不应对本申请构成任何限定。本申请并不排除在6G网络以及未来其它的网络中采用其他命名的可能。例如，在6G网络中，上述各个网元中的部分或全部可以沿用5G中的术语，也可能采用其他名称等。
为了便于理解本申请的实施例，下面对本申请的实施例涉及的一些术语或技术进行简单说明。
1、CU-DU分离架构
图2是CU-DU架构的一个示意图。
如图2所示，基站逻辑上可以划分为一个CU以及一个或多个DU。每个DU通过F1逻辑接口与CU连接。无线链路控制(Radio Link Control，RLC)层、介质接入控制(Media Access Control，MAC)层、以及物理层(Physical Layer，PHY)相关的操作由DU处理，服务数据适配协议(Service Data Adaptation Protocol，SDAP)层，无线资源控制(Radio Resource Control，RRC)层和分组数据汇聚协议(Packet Data Convergence Protocol，PDCP)层相关的操作由CU处理。
2、LTM
LTM中的L1指的PHY，L2指的MAC层、RLC层、PDCP层和SDAP层。
LTM指的是切换相关的操作主要在L1和/或L2进行。例如，终端设备将L1测量结果通过物理层控制信令发送给基站，其中物理层控制信令可以承载在物理上行控制信道(Physical Uplink Control Channel，PUCCH)；基站的物理层读取L1测量结果，并根据L1测量结果做出的切换判决，进而通过L1/L2信令将切换判决发送给终端设备，其中L1/L2信令可以是承载在物理下行控制信道(Physical Downlink Control Channel，PDCCH)的消息，也可以是MAC控制元素(MAC Control Element，MAC CE)。
需要指出的是，L1/L2表示L1和/或L2。当为“和”的关系时，切换过程相关的操作主要由L1和L2共同完成；当为“或”的关系时，切换相关的操作主要由L1或L2完成。
3、同一个CU下不同DU之间的LTM切换
图3是同一个CU下不同DU之间的LTM切换的示意性流程图。其中，S-DU指源DU(source DU)，T-DU指目标DU(target DU)，源DU和目标DU属于同一个CU。目标DU为候选DU中的一个，在切换之前，可能存在多个候选DU，在切换时，某一个候选DU成为目标DU，图3中仅示出了CU与目标DU的信令交互。
步骤301，CU从候选DU获得候选小区配置信息。
其中，候选小区可以有一个或多个。候选DU也可以有一个或多个。当有多个候选DU时，CU从每个候选DU获取该DU下的候选小区的配置信息。
一个完整的候选小区配置信息可以包括CU生成的部分和DU生成的部分，CU生成的部分可以描述为“CU侧配置信息”，DU生成的部分可以描述为“DU侧配置信息”。这里的候选小区配置信息指的是“DU侧配置信息”。
步骤302，CU经由源DU将候选小区配置信息发送给终端设备。
这里的候选小区配置信息可以指完整的候选小区配置信息，即“CU侧配置信息”和“DU侧配置信息”。
步骤303，终端设备进行小区测量，并将测量结果上报给源DU。
在LTM切换中，终端设备上报的是L1测量结果，终端设备将不同小区的L1测量结果通过源小区的通信资源发送给源DU。其中，L1测量结果包括以下至少一项：源小区的L1测量结果、或至少一个候选小区的L1测量结果。
上述源小区和/或候选小区的L1测量结果可以是小区级别的测量结果，也可以是波束级别的测量结果。
步骤304，源DU根据终端设备上报的L1测量结果，确定将终端设备切换至目标小区，并向终端设备发送切换命令。
其中，目标小区为候选小区中的一个。切换命令中包括目标小区的标识信息。切换命令可以通过L1/L2信令发送给终端设备，该L1/L2信令仍经由源小区的通信资源发送，该L1/L2信令可以是一个MAC CE。
源DU也可将触发了小区切换的情况发送给CU。
步骤305，终端设备执行LTM切换，切换至目标小区。
具体地，终端设备使用步骤302中收到的目标小区的配置信息接入目标小区。
在终端设备成功接入目标小区后，终端设备与目标小区进行上下行数据的传输。
步骤306，在终端设备成功接入目标小区后，目标DU向CU发送切换成功通知，以通知终端设备成功切换至目标小区。
由图3可知，在LTM切换中，在切换之前，基站会将候选小区的配置信息预配置给终端设备。
4、跨基站的小区切换过程中的数据转发和路径切换
1)数据转发
发送给终端设备的下行数据由核心网的UPF发给基站，再由基站发送给终端设备。
在移动通信系统中，终端设备的位置移动可能会导致终端设备与基站之间的通信链路发生变化，基站会根据终端设备的移动情况指示终端设备进行小区切换。
在切换之前，UPF与源基站之间建立有用户面传输承载，下行数据可以通过UPF与源基站之间的用户面传输承载发送至源基站，进一步由源基站发送给终端设备。随着终端设备的位置移动，在需要进行小区切换时，源基站会向终端设备发送切换命令，此后源基站无法再向终端设备发送来自UPF的下行数据，在此情况下，源基站可以将缓存在源基站的下行数据发送给目标基站，以便在切换完成后，由目标基站发送给终端设备，从而保证数据的无损。数据由源基站转发至目标基站的过程称作数据转发(data forwarding)。
上述用户面传输承载也可以描述为用户面通道、用户面隧道、用户面数据通道或用户面数据隧道等。
2)路径切换
在终端设备成功切换到目标基站后，目标基站可以将源基站转发来的数据发送给终端设备。但是，由于此时UPF尚未建立与目标基站之间的用户面传输承载，因此目标基站需要向核心网的AMF发送路径切换(path switch)请求消息，以请求将建立UPF与目标基站之间的用户面传输承载。在接收到目标基站的路径切换请求消息后，AMF可以控制UPF建立与目标基站之间的用户面传输承载。此后，UPF可以将下行数据直接发送给目标基站，而无需通过源基站的数据转发。
下面结合图4对跨基站的小区切换中的数据转发和路径切换进行描述。
图4是跨基站的小区切换的示意性流程图。图4以下行数据的传输为例进行说明。
步骤401，当源基站判断需要对终端设备进行切换时，源基站向目标基站发送切换请求消息。
步骤402，当目标基站允许终端设备接入时，目标基站向源基站发送切换请求响应消息。
其中，切换请求响应消息可以包括目标小区的配置信息。
步骤403，在接收到切换请求响应消息后，源基站向终端设备发送切换命令。
其中，切换命令中包括了目标小区的配置信息。
步骤404，在源基站向终端设备发送切换命令后，源基站将来自UPF的下行数据转发至目标基站。
在源基站向终端设备发送切换命令后，源基站无法再向终端设备发送下行数据，源基站将缓存在源基站的下行数据发送给目标基站，以便在终端设备接入目标小区后，由目标基站发送给终端设备。
步骤405，终端设备根据接收到的切换命令，采用目标小区的配置信息接入目标小区。
步骤406，在终端设备成功接入目标小区后，目标基站向AMF发送路径切换请求消息。
步骤407，AMF控制UPF进行路径切换，建立UPF与目标基站之间的用户面传输承载。
步骤408，在步骤407之后，UPF可以将发送给终端设备的下行数据发送给目标基站，无需经过源基站的数据转发。
步骤409，AMF向目标基站发送路径切换请求响应消息。
步骤410，目标基站将数据发送给终端设备。
其中，下行数据包括源基站转发来的下行数据、以及直接来自UPF的下行数据。需要说明的是，对于源基站转发来的下行数据，目标基站可以在步骤405之后就向终端设备发送。
跨基站的小区切换的更详细的描述可以参考现有技术，在此不再详述。上述步骤404示出了跨基站的小区切换过程中的数据转发，上述步骤406～409示出了跨基站的小区切换过程中的路径切换。
目前，一个下行数据从UPF到终端设备需要在特定时长内发送完成，例如在20ms内完成。如上文所示，在切换过程中，有些数据需经过源基站到目标基站的数据转发过程，这段额外的时延可能导致这些数据(尤其是时延敏感类业务的数据)到达终端设备时已经超过了该特定时长，超过了该特定时长的数据会失效，对于终端设备来说已经不可用，这样会造成业务体验下降。
针对上述问题，本申请提供了一种切换方法，可以通过将路径切换流程提前，来减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，进而提升业务体验。
下面对本申请提供的方法实施例进行描述。
本申请的实施例可以应用于不同CU下不同DU之间的LTM切换，也可以应用于其他类似的切换场景和切换技术中，不予限制。需要说明的是，以下各方法实施例中的步骤的编号的大小并不意味执行顺序的先后，各步骤的先后顺序可以由内在逻辑来确定，下文所描述的步骤的先后顺序也仅为示例，不局限于此。
图5是本申请提供的切换方法500的示意性流程图。方法500包括以下内容中的至少部分内容。
步骤501，接收第一通知消息。
其中，第一通知消息用于指示终端设备将切换至的目标小区。目标小区是目标CU下的目标DU的小区。
步骤502，根据第一通知消息，向核心网设备发送第一请求消息。
其中，第一请求消息用于请求将终端设备的用户面承载切换至目标CU。用户面承载也可以描述为用户面传输承载、用户面通道或用户面隧道等。终端设备的用户面承载可以理解为用于传输终端设备的用户面数据的承载、通道或隧道等。
相较于在接收到终端设备成功接入目标小区的指示后再发起终端设备的用户面承载的切换，方法500可以根据用于指示终端设备将切换至的目标小区的第一通知消息来发起终端设备的用户面承载的切换，换句话说，终端设备的用户面承载的切换可以由第一通知消息触发，这样可以更早的执行终端设备的用户面承载的切换。而在执行终端设备的用户面承载的切换后，终端设备的业务数据可以直接发送给目标CU，无需再经过源CU向目标CU的数据转发过程。因此，基于方法500，可以减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，进而提升业务体验。
方法500可以由源CU或源CU中的模块或单元执行，也可以由目标CU或目标CU中的模块或单元执行，下文统一使用源CU或目标CU的进行描述。
下面将结合图6对由源CU或源CU中的模块或单元执行的方案进行详细描述。
图6是本申请提供的切换方法600的示意性流程图。方法600可以包括以下内容的至少部分内容。
步骤601，源DU向源CU发送通知消息#1，或者说，源CU接收来自源DU的通知消息#1。
其中，通知消息#1可以对应于方法500中的第一通知消息，用于指示终端设备将切换至的目标小区。通知消息#1用于指示终端设备将切换至的目标小区，也可以描述为：通知消息#1用于指示终端设备将切换至目标小区，或者，第一通知消息用于向源CU通知针对终端设备的LTM命令的发起和目标小区的标识。
一种可能的实现方式，源DU可以根据终端设备上报的L1测量结果，确定将终端设备切换至目标小区，在确定将终端设备切换至目标小区后，向源CU发送通知消息#1。
步骤602，源CU根据通知消息#1，向核心网设备发送请求消息#1。
其中，请求消息#1可以对应于方法500中的第一请求消息，用于请求将终端设备的用户面承载切换至目标CU。
示例性地，请求消息#1可以为路径切换请求消息。
请求消息#1用于请求将终端设备的用户面承载切换至目标CU，也可以替换为：请求消息#1用于请求将终端设备的用户面传输承载的下行终结点切换至目标小区对应的用户面传输承载的下行终结点，其中，目标小区对应的用户面传输承载的下行终结点可以是目标小区所属的目标CU。
示例性地，核心网设备可以为AMF。AMF在接收到请求消息#1之后可以控制UPF进行将终端设备的用户面承载切换至目标CU。
这样，在方法600中，源CU可以根据用于指示终端设备将切换至的目标小区的通知消息#1来发起终端设备的用户面承载的切换，可以更早的执行终端设备的用户面承载的切换过程，从而减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，提升业务体验。
本申请的实施例不限定步骤602的具体实现方式。
第1种可能的实现方式，通知消息#1包括目标小区的第一标识，步骤602具体可以包括：源CU根据通知消息#1中的目标小区的第一标识、以及第一关联关系，向核心网设备发送请求消息#1，其中，第一关联关系用于指示目标小区的第一标识与第一信息的关联关系，第一信息用于指示目标CU的用户面承载的通道信息，请求消息#1可以包括第一信息。
示例性地，第一信息可以包括以下信息中的至少一个：目标CU的用户面承载的下行终结点的IP地址、或目标CU的用户面承载的下行终结点的GTP-TEID。
第一信息用于指示目标CU的用户面承载的通道信息，也可以替换为：第一信息用于指示目标小区对应的用户面承载的通道信息。需要说明的是，在本申请的实施例中，一个CU管理的小区中的每个小区可以分别对应一个用户面承载的通道信息，或者一个候选CU管理的小区也可以对应于相同的用户面承载的通道信息，不予限制。
本申请的实施例不限定第一关联关系的获取方式。
一种可能的实现方式，第一关联关系是预配置的。示例性地，在步骤602之前，方法600还可以包括步骤603-605，具体如下。
步骤603，源CU向目标CU发送请求消息#2，或者说目标CU接收来自源CU的请求消息#2。
其中，请求消息#2用于请求目标CU的用户面承载的通道信息，即上述第一信息。
一种可能的实现方式，请求消息#2可以是对用于请求候选小区配置信息的消息的复用或强化。换句话说，源CU可以在向目标CU请求候选小区配置信息时同时请求目标CU的用户面承载的通道信息。目标CU的用户面承载的通道信息的请求可以采用显示方式或隐示方式，不予限制。例如，源CU可以在用于请求候选小区配置信息的消息中增加额外的信息，如目标CU的标识，用以表明请求目标CU的用户面承载的通道信息。又例如，源CU可以发送用于请求候选小区配置信息的消息，该消息本身就可以表明请求目标CU的用户面承载的通道信息。
步骤604，在接收到请求消息#2后，目标CU向源CU发送请求消息#2的响应消息，即图6中的响应消息#2。相应地，源CU接收来自目标CU的响应消息#2。
其中，响应消息#2包括第一信息。
步骤605，源CU根据第一信息，确定第一关联关系。
一种可能的实现方式，源CU根据目标小区、目标CU管理的小区、以及第一信息，确定第一关联关系。示例性地，在源CU知道目标CU管理的小区的情况下，源CU接收到第一信息后可以生成目标CU管理的小区与第一信息的关联关系，由于目标CU管理的小区包括目标小区，因此生成的关联关系中包括第一关联关系。
另一种可能的实现方式，响应消息#2还包括目标小区的第二标识，在此情况下，源CU可以根据响应消息#2中的目标小区的第二标识和第一信息，生成第一关联关系。在本申请的实施例中，目标小区的第一标识可以为目标小区在空口的标识，目标小区的第二标识可以为目标小区在网络侧标识。目标小区的第一标识和目标小区的第二标识可以相同，也可以不同。当目标小区的第一标识和目标小区的第二标识不同时，可以避免在空口暴露候选小区的真实身份信息，使得通信系统更为安全。
可选地，目标小区的第一标识的长度小于目标小区的第二标识的长度。这样，可以减少空口的信令开销。
对于目标小区的第一标识和目标小区的第二标识不相同的情况，源CU根据响应消息#2中的目标小区的第二标识和第一信息，生成第一关联关系，具体可以包括：源CU可以将响应消息#2包括的目标小区的第二标识转换为第一标识，然后生成第一标识与第一信息的关联关系，即第一关联关系。
需要说明的是，图6中仅示出了目标小区所属的目标DU和目标CU相关的信令交互、以及确定第一关联关系，实际上步骤603-605可能涉及源CU与包括目标CU在内的至少一个候选CU的信令交互，以及涉及确定包括目标小区在内的至少一个候选小区与对应的候选CU的用户面承载的通道信息的关联关系。
在另一些实施例中，方法600还可以包括步骤606：源CU向目标CU发送至少一个关联关系，或者说目标CU接收来自源CU的至少一个关联关系。其中，至少一个关联关系为通过步骤603-605生成的至少一个候选小区与对应的候选CU的用户面承载的通道信息的关联关系，至少一个关联关系包括上述第一关联关系。基于此，目标CU在作为后续切换的源CU时，可以不需要重新执行步骤603-604来获得候选小区与对应的候选CU的用户面承载的通道信息的关联关系，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。
图6仅以源CU向目标CU发送至少一个关联关系为例，实际上源CU可以向全部候选CU发送该至少一个关联关系。
本申请不限定执行步骤606的时机。例如，如图6所示，源CU可以在确定至少一个关联关系后就向候选小区发送。又例如，源CU可以在获知终端设备成功接入目标小区后向目标CU和/或候选CU发送至少一个关联关系。
第2种可能的实现方式，通知消息#1包括目标小区的第一标识，步骤602具体可以包括：源CU根据通知消息#1中的目标小区的第一标识、以及第二关联关系，向核心网设备发送请求消息#1，其中，第二关联关系用于指示目标CU与第一信息的关联关系，第一信息用于指示目标CU的用户面承载的通道信息，请求消息#1可以包括第一信息。
示例性地，源CU根据通知消息#1中的目标小区的第一标识、以及目标CU管理的小区，确定目标小区所属的目标CU的标识，进而根据目标CU的标识、以及第二关联关系，向核心网设备发送请求消息#1。
本申请的实施例不限定第二关联关系的获取方式。
一种可能的实现方式，第二关联关系是预配置的。与第一关联关系的获取方式类似，可以参考步骤603-605，不同的是，响应消息#2可以包括目标CU的标识和第一信息，从而源CU可生成目标CU的标识与第一信息的对应关系。
与步骤606类似，方法600还可以包括：源CU向目标CU发送至少一个关联关系，或者说目标CU接收来自源CU的至少一个关联关系。其中，关联关系为候选CU与其用户面承载的通道信息的关联关系，至少一个关联关系包括上述第二关联关系。基于此，目标CU在作为后续切换的源CU时，可以不需要重新获得候选CU与用户面承载的通道信息的关联关系，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。更详细的描述可以参考步骤606。
此外，考虑到目标小区的第一标识是源CU确定的，目标CU并不知道，因此方法600还可以包括步骤607：源CU向目标CU发送目标小区的第一标识与目标小区的第二标识的对应关系，以便目标CU获知目标小区的第一标识与目标小区的第二标识的对应关系。
同样，图6仅以源CU向目标CU发送目标小区的第一标识与目标小区的第二标识的对应关系为例，实际上源CU可以向全部候选CU中的每一个CU发送全部候选小区的第一标识和第二标识的对应关系。
这样，包括源CU和目标CU在内的多个CU在与终端通信时，可以使用相同的候选小区的第一标识，可以避免重复配置终端设备。
本申请不限定发送目标小区的第一标识与目标小区的第二标识的对应关系的实现方式。一种可能的实现方式，目标小区的第一标识与目标小区的第二标识的对应关系可以随至少一个关联关系一起发送给候选CU。另一种可能的实现方式，若源CU知道个候选CU管理的小区，则源CU可以提前进行候选小区身份标识的转换，并在步骤603的请求消息#2中携带目标小区的第一标识与目标小区的第二标识的对应关系。
在本申请的实施例中，由源CU发起终端设备的用户面承载的切换可以是协议规定好的，也可以是源CU与目标CU协商确定的。下面对由源CU于目标CU协商的情况进行描述。
本申请不限定源CU于目标CU协商的具体实现方式。
一种可能的实现方式，源CU可以在步骤603的请求消息#2中携带第二信息，第二信息用于请求由 源CU发起终端设备的用户面承载的切换，即路径切换。相应地，目标CU可以在步骤604的响应消息#2中携带第三信息，第三信息用于指示允许由源CU发起终端设备的用户面承载的切换。在此情况下，源CU可以确定由自己发起终端设备的用户面承载的切换。
另一种可能的实现方式，源CU可以在步骤603的请求消息#2中携带第四信息，第四信息用于指示由源CU发起终端设备的用户面承载的切换。换句话说，源CU确定由自己发起终端设备的用户面承载的切换后通知目标CU即可，无需目标CU的许可。
在另一些实施例中，方法600还可以包括步骤608和609，具体如下。
步骤608，在接收到通知消息#1后，源CU向目标CU发送通知消息#2，或者说，目标CU接收来自源CU的通知消息#2。
其中，通知消息#2用于指示终端设备将切换至的目标小区，或者用于指示终端设备将切换至目标小区。
示例性地，通知消息#2可以包括以下信息中的至少一个：目标小区的第一标识、波束信息、或接入信息。其中，波束信息用于指示目标小区与终端设备通信所使用的波束方向。接入信息用于指示终端设备接入目标小区所采用的接入方式，例如基于随机接入的接入方式，或者基于免随机接入的接入方式。
步骤609，在接收到通知消息#2后，目标CU向目标DU发送通知消息#3，或者说，目标DU接收来自目标CU的通知消息#3。
其中，通知消息#3用于指示终端设备将切换至的目标小区，或者用于指示终端设备将切换至目标小区。
示例性地，通知消息#3可以包括以下信息中的至少一个：目标小区的第一标识、波束信息、或接入信息，以便目标DU使用这些信息执行与终端设备的接入过程。
一种可能的实现方式，步骤608中的通知消息#2还可以包括第七信息，其中第七信息用于指示源CU已经发起了终端设备的用户面承载的切换。例如，在源CU和目标CU未协商由谁发起终端设备的用户面承载的切换、且源CU已经发送了请求消息#1的情况下，通知消息#2中可以携带第七信息，以便目标CU根据第七信息不发起终端设备的用户面承载的切换。
在另一些实施例中，方法600还可以包括步骤610和611，具体如下。
步骤610，源CU根据通知消息#1，向目标CU转发缓存在源CU的终端设备的业务数据#1，以便在终端设备接入目标小区后，由目标基站发送给终端设备。
步骤611，在接收到业务数据#1后，目标CU向目标DU发送业务数据#1。
一种可能的实现方式，目标CU可以在确定终端设备成功接入目标小区后，向目标DU发送业务数据#1。示例性地，目标CU可以在接收到如步骤612所示的通知消息#4后向目标DU发送业务数据#1，其中通知消息#4用于指示终端设备成功接入目标小区。这样可以避免致业务数据#1向目标DU的无效传输。
另一种可能的实现方式，目标CU可以在接收到通知消息#2后就向目标DU发送业务数据#1。这样，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU可以立即向终端设备发送数据，从而有利于尽早将数据发送给终端设备，避免数据失效。
在另一些实施例中，方法600还可以包括步骤613：源CU接收来自核心网设备的响应消息#1，响应消息#1用于指示终端设备的用户面承载的切换成功或者用于指示终端设备的用户面承载的切换失败。
在另一些实施例中，方法600还可以包括步骤614：目标CU接收来自核心网设备的通知消息#5，通知消息#5用于指示以下信息中的一项：
1)已成功完成用户面承载切换的协议数据单元(Protocol Data Unit，PDU)会话标识(identifier，ID)、以及PDU会话ID对应的上行用户面承载的通道信息；
2)未成功完成用户面承载切换的PDU会话ID、以及未完成的原因。
在另一些实施例中，方法600还可以包括步骤615：在接收到通知消息#4后，目标CU向源CU发送通知消息#6，或者说源CU接收来自目标CU的通知消息#6，通知消息#6用于指示终端设备已经成功接入所述目标小区，以便源CU对终端设备在源小区的配置信息和上下文信息进行处理。
需要说明的是，上述各消息、信息、数据的名称和编号仅为示例性的，本申请对于消息和信息的名称和编号并不限定。例如，请求消息#1、请求消息#2、响应消息#1、响应消息#2、通知消息#1、通知消息#2、通知消息#3、通知消息#4、通知消息#5、通知消息#6也可以分别编号为第一请求消息、第二请求消息、第一响应消息、第二响应消息、第一通知消息、第二通知消息、第六通知消息、第四通知消息、 第七通知消息、第五通知消息。
下面结合图7对由目标CU或目标CU中的模块或单元执行的方案进行详细描述。
图7是本申请提供的切换方法700的示意性流程图。方法700可以包括以下内容的至少部分内容。
步骤701，源DU向源CU发送通知消息#7，或者说，源CU接收来自源DU的通知消息#7。步骤701可以参考步骤601，不再详述。
步骤702，在接收到通知消息#7后，源CU向目标CU发送通知消息#8，或者说，目标CU接收来自源CU的通知消息#8。
其中，通知消息#8可以对应于方法500中的第一通知消息，用于指示终端设备将切换至的目标小区。通知消息#8用于指示终端设备将切换至的目标小区，也可以描述为：通知消息#1用于指示终端设备将切换至目标小区，或者，第一通知消息用于向源CU通知针对终端设备的LTM命令的发起和目标小区的标识。
步骤703，目标CU根据通知消息#8，向核心网设备发送请求消息#3。
其中，请求消息#3可以对应于方法500中的第一请求消息，用于请求将终端设备的用户面承载切换至目标CU。请求消息#3的描述可以参考请求消息#1，在此不再详述。
目标CU向核心网设备发送请求消息#3的实现方式可以参考现有标准中的路径切换过程，不再详述。
示例性地，核心网设备可以为AMF。AMF在接收到请求消息#3之后可以控制UPF进行将终端设备的用户面承载切换至目标CU。
这样，在方法700中，目标CU可以根据用于指示终端设备将切换至的目标小区的通知消息#8来发起终端设备的用户面承载的切换，可以更早的执行终端设备的用户面承载的切换过程，从而减少经由源CU到目标CU的数据转发的数据，从而减少失效的数据，提升业务体验。
在本申请的实施例中，由目标CU发起终端设备的用户面承载的切换可以是协议规定好的，也可以是源CU与目标CU协商确定的。
本申请不限定源CU于目标CU协商的具体实现方式。
一种可能的实现方式，方法700可以包括步骤704和705，具体如下。
步骤704，源CU向目标CU发送请求消息#4，或者说目标CU接收来自源CU的请求消息#4。
其中，请求消息#4用于请求第一信息，第一信息用于指示目标CU的用户面承载的通道信息。请求消息#4的描述可以参考请求消息#2。第一信息可以参考步骤602中的描述。
源CU可以在步骤704的请求消息#4中携带第二信息，第二信息用于请求由源CU发起终端设备的用户面承载的切换，即路径切换。
步骤705，在接收到请求消息#4后，目标CU向源CU发送请求消息#4的响应消息，即图7中的响应消息#4。
其中，响应消息#4包括第六信息。第六信息用于指示不允许由源CU发起终端设备的用户面承载的切换。在此情况下，后续由目标CU发起终端设备的用户面承载的切换。
需要说明的是，图7中仅示出了目标小区所属的目标DU和目标CU相关的信令交互，实际上步骤704-705可能涉及源CU与包括目标CU在内的至少一个候选CU的信令交互，若存在其他候选CU允许由源CU发起终端设备的用户面承载切换、并向源CU提供了其用户面承载的通道信息，源CU可以确定该候选CU的候选小区与该候选小区的用户面承载的通道信息的关联关系，或者确定该候选CU与该候选小区的用户面承载的通道信息的关联关系，具体实现方式可以参考步骤603-605。
在另一些实施例中，若源CU确定了其他候选CU的候选小区与该候选小区的用户面承载的通道信息的关联关系，或者确定了其他候选CU与该候选小区的用户面承载的通道信息的关联关系，则源CU可以向包括目标CU在内的至少一个候选CU发送确定的关联关系。基于此，目标CU在作为后续切换的源CU时，可以不需要重新执行步骤704-705，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。
在另一些实施例中，与方法600类似，若源CU对包括目标小区在内的至少一个候选小区的标识进行了转换，如从第一标识转换为第二标识，则方法700还可以包括步骤706：源CU向目标CU发送至少一个候选小区的标识的第一标识与至少一个候选小区的第二标识的对应关系，具体实现方式可以参考步骤607。这样，包括源CU和目标CU在内的多个CU在与终端通信时，可以使用相同的候选小区的第一标识，可以避免重复配置终端设备。
在另一些实施例中，步骤702中的通知消息#8还可以包括以下信息中的至少一个：目标小区的第一标识、波束信息、或接入信息。其中，波束信息用于指示目标小区与终端设备通信所使用的波束方向。接入信息用于指示终端设备接入目标小区所采用的接入方式，例如基于随机接入的接入方式，或者基于免随机接入的接入方式。在此情况下，方法700还可以包括步骤707：在接收到通知消息#8后，目标CU向目标DU发送通知消息#9，或者说目标DU接收来自目标CU的通知消息#9。
其中，通知消息#9用于指示终端设备将切换至的目标小区，或者用于指示终端设备将切换至目标小区。
示例性地，通知消息#9可以包括以下信息中的至少一个：目标小区的第一标识、波束信息、或接入信息，以便目标DU使用这些信息执行与终端设备的接入过程。
在另一些实施例中，步骤702中的通知消息#8还可以包括第五信息，其中第五信息用于指示源CU未发起终端设备的用户面承载的切换。例如，在源CU和目标CU未协商由谁发起终端设备的用户面承载的切换、且源CU未发起终端设备的用户面承载的切换的情况下，通知消息#8可以携带第五信息，以便目标CU发起终端设备的用户面承载的切换。
在另一些实施例中，方法700还可以包括步骤708和709，具体如下。
步骤708，源CU根据通知消息#7，向目标CU转发缓存在源CU的终端设备的业务数据#2，以便在终端设备接入目标小区后，由目标基站发送给终端设备。
步骤709，在接收到业务数据#2后，目标CU向目标DU发送业务数据#2。
一种可能的实现方式，目标CU可以在确定终端设备成功接入目标小区后，向目标DU发送业务数据#2。示例性地，目标CU可以在接收到如步骤710所示的通知消息#10后向目标DU发送业务数据#2，其中通知消息#10用于指示终端设备成功接入目标小区。这样可以避免致业务数据#2向目标DU的无效传输。
另一种可能的实现方式，目标CU可以在接收到通知消息#8后就向目标DU发送业务数据#2。这样，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU可以立即向终端设备发送数据，从而有利于尽早将数据发送给终端设备，避免数据失效。
在另一些实施例中，方法700还可以包括步骤711：目标CU接收来自核心网设备的响应消息#3，响应消息#3用于指示终端设备的用户面承载的切换成功或者用于指示终端设备的用户面承载的切换失败。
在另一些实施例中，方法700还可以包括步骤712：在接收到通知消息#10后，目标CU向源CU通知消息#11，或者说源CU接收来自目标CU的通知消息#11，通知消息#11用于指示终端设备已经成功接入所述目标小区，以便源CU对终端设备在源小区的配置信息和上下文信息进行处理。
需要说明的是，上述各消息、信息、数据的名称和编号仅为示例性的，本申请对于消息和信息的名称和编号并不限定。例如，请求消息#3、请求消息#4、响应消息#3、响应消息#4、通知消息#7、通知消息#8、通知消息#9、通知消息#10、通知消息#11也可以分别编号为第一请求消息、第二请求消息、第一响应消息、第二响应消息、第八通知消息、第一通知消息、第三通知消息、第四通知消息、第五通知消息。
下面结合具体的实施例对本申请的切换方法进行描述。
图8是本申请提供的切换方法800的示意性流程图。
在方法800中，源CU和目标CU可以协商确定是由源CU还是目标CU发起路径切换。方法800中的请求消息#A可以对应于上文的请求消息#2或请求消息#4，响应消息#A可以对应于上文的响应消息#2或响应消息#4，通知消息#A可以对应于上文的通知消息#1或通知消息#7，通知消息#B可以对应于上文的通知消息#5，通知消息#C可以对应于上文的通知消息#2或通知消息#8，通知消息#D可以对应于上文的通知消息#3或通知消息#9，指示信息#1、指示信息#2、指示信息#3、指示信息#4、指示信息#5、指示信息#6可以分别对应于上文的第二信息、第四信息、第三信息、第六信息、第七信息、第五信息。
方法800包括以下内容中的至少部分内容。
步骤801，源CU向候选CU发送请求消息#A，或者说，候选CU接收来自源CU的请求消息#A。
其中，请求消息#A用于请求候选小区配置信息。
一种可能的实现方式，请求消息#A中可以包括指示信息#1，指示信息#1用于请求由源CU发起路径切换。这里的指示信息#1可以用于与候选CU协商是否可以由源CU发起路径切换。
另一种可能的实现方式，请求消息#A中可以包括指示信息#2，指示信息#2用于指示由源CU发起路径切换。
这里的候选CU可以是一个或多个，是终端设备可以切换至的CU。一种可能的实现方式，候选CU可以是源CU根据来自终端设备的测量信息确定的。需要说明的是，图8所示的目标CU为候选CU中的一个，在切换之前，终端设备可以切换至的这些CU称为候选CU，在切换时，某一个候选CU成为目标CU。
步骤802，每个候选CU向候选CU下的候选DU发送请求消息#B，或者说候选CU下的候选DU接收来自候选CU的请求消息#B。
其中，请求消息#B用于请求候选小区的“DU侧配置信息”。一个完整的候选小区配置信息可以包括CU生成的部分和DU生成的部分，“CU侧配置信息”可以指CU生成的部分，“DU侧配置信息”可以指DU生成的部分。
需要说明的是，图8所示的目标DU为候选DU中的一个，在切换时，某一个候选DU成为目标DU。
步骤803，候选CU下的候选DU向候选CU发送响应消息#B，或者说候选CU接收来自候选CU下的候选DU的响应消息#B。
其中，响应消息#B包括候选小区的“DU侧配置信息”。
步骤804，候选CU向源CU发送响应消息#A，或者说源CU接收来自候选CU的响应消息#A。
其中，响应消息#A包括候选小区配置信息，该候选小区配置信息包括上文所述的“CU侧配置信息”和“DU侧配置信息”。
当请求消息#A中携带指示信息#1且候选CU允许由源CU发起路径切换时，除候选小区配置信息以外，响应消息#A还可以包括以下信息中的至少一项：候选小区的身份标识、指示信息#3、或候选CU的用户面承载的通道信息。这些信息可以供源CU在发起路径切换时使用。其中，指示信息#3用于指示候选CU许可由源CU发起路径切换。
当请求消息#A中携带指示信息#1，且候选CU不允许由源CU发起路径切换时，除候选小区配置信息以外，响应消息#A还可以包括以下信息中的至少一项：候选小区的身份标识、或指示信息#4。其中，指示信息#4用于指示候选CU不允许由源CU发起路径切换。
当请求消息#A中携带指示信息#2时，除候选小区配置信息以外，响应消息#A还可以包括以下信息中的至少一项：候选小区的身份标识、或候选CU的用户面承载的通道信息。
若请求消息#A中携带指示信息#2，则后续可以由源CU发起路径切换。若响应消息#A包括指示信息#3，即候选CU许可由源CU发起路径切换，则后续可以由源CU发起路径切换。若响应消息#A包括指示信息#4，即候选CU不允许由源CU发起路径切换时，则后续可以由候选CU发起路径切换。
上述候选小区的身份标识为可以唯一确定候选小区的信息，例如候选小区的身份标识信息可以包括候选小区的全球小区标识(cell global identifier，CGI)或物理小区标识(physical cell ID，PCI)中的至少一项。
上述候选CU的用户面承载的通道信息，也可以称为候选CU的用户面承载的隧道信息，用于指示由UPF发往候选CU的数据的终结点。示例性地，用户面承载的通道信息可以是NG-U用户面传输网络层信息(NG-U user plane transport network layer information，NG-U UP TNL Information)，其中NG-U为UPF与CU之间的接口名称，是协议中定义的接口名称，NG-U指下一代用户面(next generation-user plane)。例如，用户面承载的通道信息可以包括以下信息中的至少一项：终结点的IP地址、或终结点的GTP-TEID。
需要说明的是，候选CU的用户面承载可以指候选CU的PDU会话。在一种可能的实现方式中，同一个候选CU的PDU会话中的每个PDU会话可以分别对应一个用户面承载的通道信息，例如，不同的业务类型对应着不同的PDU会话，每个PDU会话有自己的用户面承载的通道信息。在另一种可能的实现方式中，同一个候选CU的PDU会话也可以对应于相同的用户面承载的通道信息。
还需要说明的是，图8中仅示出了候选小区中被选为目标小区所属的目标DU和目标CU相关的信令交互，实际上步骤801～804可能涉及一个或多个候选CU、以及一个或多个候选DU的信令交互。
步骤805，基于每个候选CU的响应消息#A，源CU可以确定候选小区与该候选小区对应的候选CU的用户面承载的通道信息的关联关系。
示例性地，源CU可以基于响应消息#A中的候选小区的身份标识信息、指示信息#3、和候选CU的用户面承载的通道信息，确定候选小区与候选小区对应的候选CU的用户面承载的通道信息的关联关系。
例如，源CU可以基于响应消息#A中的指示信息#3，确定由源CU发起路径切换，进而根据响应消 息#A中的候选小区的身份标识信息和候选CU的用户面承载的通道信息，确定候选小区与候选小区对应的候选CU的用户面承载的通道信息的关联关系。
一种可能的实现方式，源CU可以生成响应消息#A包括的候选小区的身份标识与其对应的候选CU的用户面承载的通道信息的关联关系。
另一种可能的实现方式，源CU可以将响应消息#A包括的候选小区的身份标识转换为新的标识，然后生成新的标识与候选CU的用户面承载的通道信息的关联关系。
示例性地，当响应消息#A包括的候选小区的身份标识为CGI或PCI时，源CU可以将候选小区的CGI或PCI转换为更简短的候选小区ID，例如取值范围为0-7的ID；然后生成候选小区ID与候选CU的用户面承载的通道信息的关联关系。在此情况下，后续的通信过程中源CU可以使用候选小区ID与终端设备和/或其他网元进行通信。这样，可以减少信令开销，也可以避免在空口暴露候选小区的真实身份信息，使得通信系统更为安全。
需要说明的是，对于发送包括指示信息#4的响应消息#A的候选CU，由于该候选CU不允许由源CU发起路径切换，该候选CU未向源CU提供其用户面承载的通道信息，因此源CU不会确定该候选CU管理的候选小区与该候选CU的用户面承载的通道信息的关联关系，换句话说，在步骤805后源CU中没有该候选CU管理的候选小区与该候选CU的用户面承载的通道信息的关联关系。
步骤806，源CU将接收到的候选小区配置信息发送给终端设备，或者说终端设备接收来自源CU的候选小区配置信息。
步骤807，源DU确定将终端设备切换至目标小区。
在步骤806和步骤807之间，可以执行终端设备上报候选小区和服务小区的测量结果的步骤，图8中未示出。源DU可以根据终端设备上报的测量结果，确定从候选小区中确定目标小区。
步骤808，源DU向终端设备发送切换命令，或者说终端设备接收来自源DU的切换命令。
其中，切换命令包括目标小区的身份标识，例如步骤805中源CU生成的候选小区ID，此时候选小区ID成为目标小区ID。
步骤809，源DU向源CU发送通知消息#A，或者说源CU接收来自源DU的通知消息#A。
其中，通知消息#A用于指示终端设备将切换至目标小区。通知消息#A包括目标小区的身份标识，例如步骤805中源CU生成的候选小区ID，此时候选小区ID成为目标小区ID。
针对目标CU发送的响应消息#A的不同情况，后续执行的步骤也不同，下面分情况进行描述。
情况1：目标CU发送的响应消息#A包括指示信息#3，即候选CU许可由源CU发起路径切换，在此情况下，可以执行步骤810-817。
步骤810，源CU根据通知消息#A，向AMF发送路径切换请求消息，或者说，AMF接收来自源CU的路径切换消息。
其中，路径切换请求消息用于请求将终端设备的用户面承载切换至目标CU。路径切换请求消息中可以包括目标小区对应的用户面承载的通道信息和终端设备的身份标识。其中，终端设备的身份标识可以RAN UE NG应用协议ID(RAN UE next generation application protocol ID，RAN UE NGAP ID)。
一种可能的实现方式，源CU可以根据通知消息#A获取目标小区的身份标识，进一步根据目标小区的身份标识与目标CU的用户面承载的通道信息的关联关系，如步骤805中生成的关联关系，获得目标CU的用户面承载的通道信息，然后通过路径切换请求消息将目标CU的用户面承载的通道信息和终端设备的身份标识发送给AMF。
需要说明的是，本申请不限定源CU发送路径切换请求消息的时机。
一种可能的实现方式，如图8所示，源CU可以在接收到通知消息#A后立即发送路径切换请求消息，或者说，源CU发起的路径切换可以由通知消息#A触发，又或者说响应于通知消息#A，源CU发送路径切换请求消息。
另一种可能的实现方式，源CU可以在终端设备成功接入到目标DU后，或者说终端设备成功切换至目标DU的目标小区后，发起路径切换。
步骤811，在接收到路径切换请求消息后，AMF和UPF进行路径切换。
AMF和UPF进行路径切换的实现方式可以参考现有协议，在此不再详述。
可选地，方法800还可以包括步骤812，即AMF向源CU发送路径切换请求响应消息，用于响应步骤810中的路径切换请求消息。其中，路径切换请求响应消息用于指示是否成功完成路径切换。
可选地，方法800还可以包括步骤813，即AMF向目标CU发送通知消息#B，或者说目标CU接收来自AMF的通知消息#B。其中，通知消息#B可以包括以下信息中的一项：
1)已成功完成路径切换的PDU会话ID、以及PDU会话ID对应的上行用户面承载的通道信息；
2)未成功完成路径切换的PDU会话ID、以及未完成的原因。
步骤814，在路径切换后，UPF可以将终端设备的下行数据发送至目标CU，而不再是源CU。
步骤815，源CU还可以根据通知消息#A，向目标CU发送通知消息#C，或者说，目标CU接收来自源CU的通知消息#C。
其中，通知消息#C包括以下信息中的至少一项：目标小区的身份标识、波束信息或接入信息。其中，波束信息用于指示目标小区与终端设备通信时使用的波束方向。接入信息用于指示终端设备接入目标小区采用的接入方式，终端设备接入目标小区采用的接入方式为以下任意一个：随机接入的方式或免随机接入的方式。
可选地，若步骤801和804中源CU和目标CU未协商由谁发起路径切换，且源CU已经发送了路径切换请求消息，则通知消息#C还包括可以指示信息#5，其中指示信息#5用于指示源CU已经发起了路径切换、源CU已经执行了路径切换、或源CU执行了发送路径切换请求消息的步骤，以便目标CU判断不需要发起路径切换。
步骤816，在接收到通知消息#C后，目标CU向目标DU发送通知消息#D，或者说目标DU接收来自目标CU的通知消息#D。
其中，通知消息#D包括以下信息中的至少一项：目标小区的身份标识、波束信息或接入信息。其中，波束信息和接入信息的描述可以参考步骤815。这样，目标DU可以基于通知消息#D中的信息完成与终端设备的随机接入过程。
一种可能的实现方式，目标CU根据步骤801和804的协商结果，确定不执行路径切换。
另一种可能的实现方式，若通知消息#C中包括指示信息#5，则目标CU可以根据通知消息#C中的指示信息#5，不执行路径切换。
步骤817，在接收到通知消息#A后，源CU还可以向目标CU发送终端设备的数据，或者说，目标CU接收来自源CU的数据。即源CU可以向目标CU执行数据转发。
示例性地，对于针对终端设备的下行数据，源CU可以将尚未发送给终端设备的下行数据和/或尚未成功发送给终端设备的数据发送给目标CU。其中尚未成功发送给终端设备的数据可以包括已经发送给终端设备但尚未接收到终端设备的成功接收的反馈的数据。
示例性地，对于针对终端设备的上行数据，源CU将来自终端设备的上行数据转发给目标CU。
情况2：目标CU发送的响应消息#A包括指示信息#4，即候选不允许由源CU发起路径切换，在此情况下，可以执行步骤818-824。
步骤818，在接收到通知消息#A后，源CU可以向目标CU发送终端设备的数据，或者说，目标CU接收来自源CU的数据。详细描述可以参考步骤817。
步骤819，源CU还可以根据通知消息#A，向目标CU发送通知消息#C，或者说，目标CU接收来自源CU的通知消息#C。
其中，通知消息#C包括以下信息中的至少一项：目标小区的身份标识、波束信息或接入信息。其中，波束信息用于指示目标小区与终端设备通信时使用的波束方向。接入信息用于指示终端设备接入目标小区采用的接入方式，终端设备接入目标小区采用的接入方式为以下任意一个：随机接入的方式或免随机接入的方式。
可选地，若步骤801和804中源CU和目标CU未协商由谁发起路径切换，且源CU未发起路径切换，则通知消息#C还包括指示信息#6，其中指示信息#6用于指示源CU未发起路径切换、源CU未执行路径切换、源CU未执行发送路径切换请求消息的步骤、或由目标CU发起路径切换。
步骤820，在接收到通知消息#C后，目标CU根据通知消息#C中的目标小区的身份标识，向AMF发送路径切换请求消息，或者说，AMF接收来自目标CU的路径切换消息。
其中，路径切换请求消息的描述可以参考步骤810。
一种可能的实现方式，目标CU根据步骤801和804的协商结果，确定由自己执行路径切换，从而在接收到通知消息#C后，向AMF发送路径切换请求消息。
另一种可能的实现方式，若通知消息#C中包括指示信息#6，则目标CU可以根据指示信息#6，确定 执行路径切换，从而向AMF发送路径切换请求消息。
需要说明的是，本申请不限定目标CU发送路径切换请求消息的时机。
一种可能的实现方式，如图8所示，目标CU可以在接收到通知消息#C后立即发送路径切换请求消息，或者说，目标CU发起的路径切换可以由通知消息#C触发，又或者说响应于通知消息#C，目标CU发送路径切换请求消息。
另一种可能的实现方式，目标CU可以在终端设备成功接入到目标DU后，或者说终端设备成功切换至目标DU的目标小区后，发起路径切换。
步骤821，在接收到路径切换请求消息后，AMF和UPF进行路径切换。
AMF和UPF进行路径切换的实现方式可以参考现有协议，在此不再详述。
可选地，方法800还可以包括步骤822，即AMF向目标CU发送路径切换请求响应消息，用于响应步骤820中的路径切换请求消息。其中，路径切换请求响应消息用于指示是否成功完成路径切换。
步骤823，在路径切换后，UPF可以将终端设备的下行数据发送至目标CU，而不再是源CU。
步骤824，在接收到通知消息#C后，目标CU还可以向目标DU发送通知消息#D，或者说目标DU接收来自目标CU的通知消息#D。
其中，通知消息#D包括以下信息中的至少一项：目标小区的身份标识、波束信息或接入信息。其中，波束信息和接入信息的描述可以参考步骤815。这样，目标DU可以基于通知消息#D中的信息完成与终端设备的随机接入过程。
需要说明的是，若步骤801的请求消息#A中携带指示信息#2，则在步骤809后，可以继续执行步骤810-817。
可选地，方法800可以包括步骤825，即目标CU向目标DU进行提前的数据发送。
这里的“提前”指的是：终端设备此时可能尚未接入目标CU的目标DU的目标小区，但目标CU提前将来自源CU或UPF的终端设备的数据发送给目标DU。示例性地，在接收到第二通知消息#C后，目标CU可以执行提前的数据发送。
这样，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU可以立即向终端设备发送数据，从而有利于尽早将数据发送给终端设备，避免数据失效。
需要说明的是，在上述情况1、情况2或者请求消息#A携带指示信息#2的情况中的任意一种情况下，方法800都可以包括步骤825，不予限制。
步骤826，终端设备和目标DU执行目标小区接入过程。
在一种可能的实现方式中，步骤826具体的实现方式可以参考现有标准，不再详述。
在另一种可能的实现方式中，终端设备使用基于免随机接入的接入方式切换至目标小区。目标小区可能配置有多个载波，例如配置有两个载波，分别为NUL和SUL。针对终端设备通过免随机接入的方式切换至目标小区的NUL和SUL中的哪个载波，需要终端设备和目标接入网设备(目标CU和/或目标DU)理解一致，以保证小区切换能够成功进行。下面提供几种可能的方案：
方案1：在步骤804和步骤806提供的候选小区的配置信息中，某个候选小区仅提供了SUL的配置或仅提供了NUL的配置。当终端设备接收到步骤808的切换命令后，根据目标小区提供的SUL或NUL的配置，确定使用SUL或者NUL进行向目标小区的接入/切换。
方案2：在步骤804和步骤806提供的候选小区的配置信息中，某个候选小区提供了SUL的配置和NUL的配置，并额外有一个字段用于指示应使用SUL或者NUL。当终端设备接收到步骤808的切换命令后，根据目标小区的用于指示应使用SUL或者NUL的字段，确定使用SUL或者NUL进行向目标小区的接入/切换。
方案3：在步骤804和步骤806提供的候选小区的配置信息中，某个候选小区提供了SUL的配置和NUL的配置，且将提供了SUL和NUL的配置的情况告知源接入网设备(例如源CU和/或源DU)，由源接入网设备在某次切换时，确定目标小区应使用的上行载波。示例性地，源接入网设备根据终端设备反馈的信道测量结果，确定选择某个上行载波，并将确定的结果通过步骤808的切换命令告知终端设备，终端设备根据切换命令(例如MAC CE)中指示的载波信息，选择SUL或者NUL进行向目标小区的接入/切换。进一步可选地，源接入网设备可通过步骤809、步骤815和步骤824将选择的载波信息通知给目标接入网设备(例如目标CU和/或目标DU)。
方案4：在步骤804和步骤806提供的候选小区的配置信息中，某个候选小区提供了SUL的配置和 NUL的配置，源接入网设备(例如源CU和/或源DU)在发送步骤808的切换命令之前，与目标接入网设备(例如目标CU和/或目标DU)进行交互，该交互过程图中未示出，例如发送请求消息与接收响应消息，在响应消息中，目标接入网设备告知源接入网设备应选择目标小区的哪个上行载波，由源接入网设备在步骤808的切换命令通知给终端设备。终端设备根据切换命令(例如MAC CE)中指示的载波信息，选择SUL或者NUL进行向目标小区的接入/切换。
方案5：在步骤804和步骤806提供的候选小区的配置信息中，某个候选小区提供了SUL的配置和NUL的配置，终端设备在收到步骤808的切换命令后，根据目标小区的信道质量，选择目标小区的上行载波，例如，当目标小区的下行参考信号的参考信号接收功率(reference signal received power，RSRP)小于某一配置的门限值时，终端设备选择目标小区的SUL接入；否则选择目标小区的NUL接入。应理解，在此方案中，目标接入网设备(例如目标CU和/或目标DU)会尝试在SUL和NUL上均尝试接收终端设备发送的上行信号(例如目标接入网设备在SUL和NUL的预配置的上行授权资源接收上行消息)，或尝试在SUL和NUL均向终端设备发送下行信号(例如目标接入网设备在SUL和NUL均对终端设备进行调度信息的发送)。
需要说明的是，步骤826中的随机接入方案可以与本申请实施例的切换方法结合在一起实施，也可以作为单独的实施例，独立实施。
步骤827，在终端设备成功接入到目标CU的目标DU的目标小区后，目标DU向目标CU发送切换成功指示，以通知目标CU终端设备已成功切换至目标小区。
步骤828，在接收到切换成功指示后，目标CU向目标DU发送来自源CU或UPF的终端设备的数据。
步骤825与步骤828为目标CU向目标DU发送来自源CU或UPF的数据的两种实现方式，两者在数据的发送时机上不同。步骤825是在接收到通知消息#C后执行，而步骤828是在接收到切换成功指示后执行，两者可以择一执行。
步骤829，目标DU将接收到的数据发送给终端设备。
可选地，方法800可以包括步骤830，即目标CU向源CU发送通知消息#E，用于向源CU通知终端设备已成功接入目标小区，以便源CU对终端设备在源小区的配置信息和上下文信息进行处理。
一种可能的实现方式，源CU可以保留该终端设备在源小区的配置信息和上下文信息，以便终端设备之后切换回来后继续使用。
另一种可能的实现方式，在接收到通知消息#E后，源CU释放终端设备在源小区的配置信息和上下文信息。
可选地，方法800可以包括步骤831，即源CU向候选CU发送通知消息#F，或者说候选CU接收来自源CU的通知消息#F，其中通知消息#F包括步骤805中确定的候选小区与候选小区对应的候选CU的用户面承载的通道信息的关联关系。目标CU获知了该关联关系，便可在后续作为源CU指示终端设备进行小区切换时，根据该关联关系向AMF发送路径切换请求消息。基于此，首次切换的目标CU在作为后续切换的源CU时，可以不需要重新执行步骤801～步骤804来获得候选小区身份标识与对应的候选CU的用户面承载的通道信息的关联关系，从而可以降低信令开销，使得后续切换过程和相应的路径切换过程能较快执行。
本申请不限定执行步骤831的时机。
一种可能的实现方式，如图8所示，源CU可以在步骤830后执行，即源CU在获知终端设备成功接入目标小区后向候选CU发送通知消息#F。
另一种可能的实现方式，源CU可以在步骤805之后就执行，而无需等到终端设备成功接入目标小区。示例性地，CU#1为源CU，CU#2和CU#3为候选CU，当执行完步骤801～805后，CU#1已获取了CU#2和CU#3的候选小区身份标识与CU#2的用户面承载的通道信息的关联关系、以及CU#3的候选小区身份标识与CU#3的用户面承载的通道信息的关联关系，在步骤805之后，CU#1可将获得的关联关系发送给CU#2和CU#3，以便终端设备切换到CU#2或者CU#3之后，CU#2或CU#3能够继续向AMF发起路径切换请求。
需要说明的是，若步骤805中的关联关系为基于响应消息#A中携带的候选小区的身份标识转换得到的新标识与候选CU的用户面承载的通道信息的关联关系，则方法800还包括源CU向候选CU发送新标识与转换前的候选小区的身份标识的对应关系。
本申请不限定发送新标识与转换前的候选小区的身份标识的对应关系的实现方式。
一种可能的实现方式，新标识与转换前的候选小区的身份标识的对应关系承载于通知消息#E中，即新标识与转换前的候选小区的身份标识的对应关系可以随新标识与候选CU的用户面承载的通道信息的关联关系一起发送给候选CU。
另一种可能的实现方式，若源CU知道个候选CU管理的小区，则源CU可以提前进行候选小区身份标识的转换，并在步骤801的请求消息#A中携带新标识与转换前的候选小区的身份标识的对应关系。
需要说明的是，本申请的实施例并不限定步骤808和809的先后顺序，也不限定步骤810、815、817的先后顺序，也不限定步骤818和819的先后顺序。
图9是本申请提供的切换方法900的示意性流程图。
与方法800不同的是，路径切换由源CU发起，不需要源CU和目标CU之间的协商过程。具体地，步骤901-904可以参考步骤801-804，不同的是，请求消息#A中不需要携带指示信息#1或指示信息#2，响应消息#A中也不需要携带指示信息#3或指示信息#4。步骤905-917可以参考步骤805-818，不同的是，通知消息#C中不需要携带指示信息#5或指示信息#6。步骤918-924与步骤825-831相同，可以参考步骤825-831。
图10是本申请提供的切换方法1000的示意性流程图。
与方法800不同的是，路径切换由目标CU发起，不需要源CU和目标CU之间的协商过程。具体地，步骤1001-1004可以参考步骤801-804，不同的是，请求消息#A中不需要携带指示信息#1或指示信息#2，响应消息#A中不需要携带指示信息#3或指示信息#4，响应消息#A也不需要携带候选CU的用户面承载的通道信息。步骤1005-1008与步骤806-809相同，可以参考步骤806-809。步骤1009-1021可以参考步骤818-830，不同的是，通知消息#C中不需要携带指示信息#5或指示信息#6。
上文结合图5至图10，详细描述了本申请提供的方法实施例，下面将结合图11至图12，描述本申请的装置实施例。
可以理解的是，为了实现上述实施例中功能，图11或图12中的装置包括了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本申请中所公开的实施例描述的各示例的单元及方法步骤，本申请能够以硬件或硬件和计算机软件相结合的形式来实现。
图11和图12为本申请的实施例提供的可能的装置的结构示意图。这些装置可以用于实现上述方法实施例中源CU、目标CU、源接入网设备、目标接入网设备或终端设备的功能，因此也能实现上述方法实施例所具备的有益效果。
如图11所示，装置10包括收发单元11和处理单元12。收发单元11用于执行装置10的收发步骤。收发单元12用于执行装置10的处理步骤。
示例性地，当装置10用于实现图6中源CU的功能时，收发单元11用于执行源CU的收发步骤，如步骤601-604、606-608、610、613、615，处理单元12用于执行源CU的处理步骤，如步骤605。当装置10用于实现图6中目标CU的功能时，收发单元11用于执行目标CU的收发步骤，如步骤603、604、606-612、614-615。
示例性地，当装置10用于实现图7中源CU的功能时，收发单元11用于执行源CU的收发步骤，如步骤701-702、704-706、708、712。当装置10用于实现图7中目标CU的功能时，收发单元11用于执行目标CU的收发步骤，如步骤702-712。
示例性地，当装置10用于实现图8中步骤826中源接入网设备、目标接入网设备或终端设备的功能时，收发单元11用于执行源接入网设备、目标接入网设备或终端设备的收发步骤，处理单元12用于执行源接入网设备、目标接入网设备或终端设备的处理步骤。
关于上述收发单元11和处理单元12更详细的描述，可参考上述方法实施例中的相关描述，在此不再说明。
如图12示，装置20包括处理器21。处理器21与存储器23耦合，存储器23用于存储指令。当装置20用于实现上文所述的方法时，处理器21用于执行存储器23中的指令，以实现上述处理单元12的功能。
可选地，装置20还包括存储器23。
可选地，装置20还包括接口电路22。处理器21和接口电路22之间相互耦合。可以理解的是，接口电路22可以为收发器或输入输出接口。当装置20用于实现上文所述的方法时，处理器21用于执行指令，以实现上述处理单元12的功能，接口电路22用于实现上述收发单元11的功能。
示例性地，当装置20为应用于源CU、目标CU、源接入网设备、目标接入网设备或终端设备的芯片 时，该芯片实现上述方法实施例中源CU、目标CU、源接入网设备、目标接入网设备或终端设备的功能。该芯片从源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的其它模块(如射频模块或天线)接收信息，该信息是其他装置发送给源CU、目标CU、源接入网设备、目标接入网设备或终端设备的；或者，该芯片向源CU、目标CU、源接入网设备、目标接入网设备或终端设备中的其它模块(如射频模块或天线)发送信息，该信息是源CU、目标CU、源接入网设备、目标接入网设备或终端设备发送给其他装置的。
本申请还提供一种通信装置，包括处理器，该处理器与存储器耦合，存储器用于存储计算机程序或指令和/或数据，处理器用于执行存储器存储的计算机程序或指令，或读取存储器存储的数据，以执行上文各方法实施例中的方法。可选地，处理器为一个或多个。可选地，该通信装置包括存储器。可选地，存储器为一个或多个。可选地，该存储器与该处理器集成在一起，或者分离设置。
本申请还提供一种芯片，包括处理器，所述处理器和存储器耦合，所述存储器用于存储计算机程序或指令，所述处理器用于执行所述存储器中存储的计算机程序或指令以实现上述各方法实施例中由源CU、目标CU、源接入网设备、目标接入网设备或终端设备执行的方法。
本申请还提供一种计算机可读存储介质，其上存储有用于实现上述各方法实施例中由源CU、目标CU、源接入网设备、目标接入网设备或终端设备执行的方法的计算机指令。
本申请还提供一种计算机程序产品，包含指令，该指令被计算机执行时以实现上述各方法实施例中由源CU、目标CU、源接入网设备、目标接入网设备或终端设备执行的方法。
本申请还提供一种通信系统，该通信系统包括上文各实施例中的源CU、目标CU、源接入网设备、目标接入网设备或终端设备中至少一个。
上述提供的任一种装置中相关内容的解释及有益效果均可参考上文提供的对应的方法实施例，此处不再赘述。
可以理解的是，本申请的实施例中的处理器可以是中央处理单元(central processing unit，CPU)，还可以是其它通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现场可编程门阵列(field programmable gate array，FPGA)或者其它可编程逻辑器件、晶体管逻辑器件，硬件部件或者其任意组合。通用处理器可以是微处理器，也可以是任何常规的处理器。
本申请的实施例中的方法步骤可以通过硬件的方式来实现，也可以由处理器执行软件指令的方式来实现。软件指令可以由相应的软件模块组成，软件模块可以被存放于随机存取存储器、闪存、只读存储器、可编程只读存储器、可擦除可编程只读存储器、电可擦除可编程只读存储器、寄存器、硬盘、移动硬盘、只读光盘存储器(compact disc read-only memory，CD-ROM)或者本领域熟知的任何其它形式的存储介质中。一种示例性的存储介质耦合至处理器，从而使处理器能够从该存储介质读取信息，且可向该存储介质写入信息。当然，存储介质也可以是处理器的组成部分。处理器和存储介质可以位于ASIC中。另外，该ASIC可以位于源CU、目标CU、源接入网设备、目标接入网设备或终端设备中。当然，处理器和存储介质也可以作为分立组件存在于源CU、目标CU、源接入网设备、目标接入网设备或终端设备中。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机程序或指令。在计算机上加载和执行所述计算机程序或指令时，全部或部分地执行本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、网络设备、用户设备或者其它可编程装置。所述计算机程序或指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机程序或指令可以从一个网站站点、计算机、服务器或数据中心通过有线或无线方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是集成一个或多个可用介质的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，例如，软盘、硬盘、磁带；也可以是光介质，例如，数字视频光盘；还可以是半导体介质，例如，固态硬盘。
在本申请的各个实施例中，如果没有特殊说明以及逻辑冲突，不同的实施例之间的术语和/或描述具有一致性、且可以相互引用，不同的实施例中的技术特征根据其内在的逻辑关系可以组合形成新的实施例。
除非另有说明，本申请实施例所使用的所有技术和科学术语与本申请的技术领域的技术人员通常理解的含义相同。本申请中所使用的术语只是为了描述具体的实施例的目的，不是旨在限制本申请的范围。应理解，上述为举例说明，上文的例子仅仅是为了帮助本领域技术人员理解本申请实施例，而非要将申请实施例限制于所示例的具体数值或具体场景。本领域技术人员根据上文所给出的例子，显然可以进行各种等价的修改或变化，这样的修改和变化也落入本申请实施例的范围内。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (29)

  1. 一种切换方法，其特征在于，所述方法包括：
    接收第一通知消息，所述第一通知消息用于指示终端设备将切换至的目标小区，所述目标小区为目标集中式单元CU下的目标分布式单元DU的小区；
    根据所述第一通知消息，向核心网设备发送第一请求消息，所述第一请求消息用于请求将所述终端设备的用户面承载切换至所述目标CU。
  2. 根据权利要求1所述的方法，其特征在于，
    所述接收第一通知消息包括：接收来自源DU的所述第一通知消息。
  3. 根据权利要求2所述的方法，其特征在于，
    所述第一通知消息包括所述目标小区的第一标识；
    根据所述第一通知消息，向核心网设备发送第一请求消息，包括：根据所述第一标识、以及第一关联关系，向所述核心网设备发送所述第一请求消息，所述第一关联关系用于指示所述第一标识与第一信息的关联关系，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第一请求消息包括所述第一信息。
  4. 根据权利要求3所述的方法，其特征在于，在所述接收来自源DU的第一通知消息之前，所述方法还包括：
    向所述目标CU发送第二请求消息，所述第二请求消息用于请求所述第一信息；
    接收来自所述目标CU的第二响应消息，所述第二响应消息包括所述目标小区的第二标识和所述第一信息；
    根据所述第二标识和所述第一信息，确定所述第一关联关系。
  5. 根据权利要求4所述的方法，其特征在于，
    所述第二请求消息还包括第二信息，所述第二信息用于请求由源CU发起路径切换；
    所述第二响应消息还包括第三信息，所述第三信息用于指示允许由所述源CU发起路径切换。
  6. 根据权利要求4所述的方法，其特征在于，
    所述第二请求消息还包括第四信息，所述第四信息用于指示由源CU发起路径切换。
  7. 根据权利要求3至6中任一项所述的方法，其特征在于，所述方法还包括：
    向候选CU发送至少一个关联关系，所述候选CU包括所述目标CU，所述至少一个关联关系包括所述第一关联关系。
  8. 根据权利要求3至7中任一项所述的方法，其特征在于，
    所述第一信息包括以下信息中的至少一个：所述目标CU的用户面承载的下行终结点的互联网协议IP地址、或所述目标CU的用户面承载的下行终结点的通用分组无线系统隧道协议-隧道端点标识GTP-TEID。
  9. 根据权利要求2至8中任一项所述的方法，其特征在于，所述方法还包括：
    根据所述第一通知消息，向所述目标CU转发所述终端设备的业务数据。
  10. 根据权利要求2至9中任一项所述的方法，其特征在于，所述方法还包括：
    向所述目标CU发送第二通知消息，所述第二通知消息用于指示所述终端设备将切换至的所述目标小区。
  11. 根据权利要求10所述的方法，其特征在于，
    所述第二通知消息包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端设备通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
  12. 根据权利要求1至11中任一项所述的方法，其特征在于，所述方法还包括：
    向所述目标CU发送所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
  13. 根据权利要求1至12中任一项所述的方法，其特征在于，所述方法应用于源CU或源CU中的模块或单元。
  14. 根据权利要求1所述的方法，其特征在于，
    所述接收第一通知消息包括：接收来自源CU的所述第一通知消息。
  15. 根据权利要求14所述的方法，其特征在于，
    所述第一通知消息包括第五信息，所述第五信息用于指示所述源CU未发起路径切换。
  16. 根据权利要求14所述的方法，其特征在于，在接收来自源CU的所述第一通知消息之前，所述方法还包括：
    接收来自所述源CU的第二请求消息，所述第二请求消息用于请求第一信息，所述第一信息用于指示所述目标CU的用户面承载的通道信息，所述第二请求消息还包括第二信息，所述第二信息用于请求由所述源CU发起路径切换；
    向所述源CU发送第二响应消息，所述第二响应消息包括第六信息，所述第六信息用于指示不允许由所述源CU发起路径切换。
  17. 根据权利要求16所述的方法，其特征在于，
    所述第一信息包括以下信息中的至少一个：所述目标CU对应的用户面承载的下行终结点的互联网协议IP地址、或所述目标CU对应的用户面承载的下行终结点的通用分组无线系统隧道协议-隧道端点标识GTP-TEID。
  18. 根据权利要求14至17中任一项所述的方法，其特征在于，
    所述第一通知消息包括以下信息中的至少一个：所述目标小区的第一标识、波束信息、或接入信息，其中，所述波束信息用于指示所述目标小区与所述终端设备通信所使用的波束方向，所述接入信息用于指示所述终端设备接入所述目标小区所采用的接入方式。
  19. 根据权利要求18所述的方法，其特征在于，所述方法还包括：
    根据所述第一通知消息，向所述目标DU发送第三通知消息，所述第三通知消息包括以下信息中的至少一个：所述第一标识、所述波束信息、或所述接入信息。
  20. 根据权利要求15至19中任一项所述的方法，其特征在于，所述方法还包括：
    接收来自所述源CU的至少一个关联关系，所述关联关系用于指示候选小区的标识和所述候选小区对应的候选CU的用户面承载的通道信息的关联关系。
  21. 根据权利要求14至20中任一项所述的方法，其特征在于，所述方法还包括：
    接收来自所述源CU的所述终端设备的业务数据；
    向所述目标DU发送所述业务数据；
    在向所述目标DU发送所述业务数据之后，接收来自所述目标DU的第四通知消息，所述第四通知消息用于指示所述终端设备已经成功接入所述目标小区。
  22. 根据权利要求14至21中任一项所述的方法，其特征在于，所述方法还包括：
    接收来自所述源CU的所述目标小区的第一标识和所述目标小区的第二标识的对应关系，所述第一标识为所述目标小区在空口的标识，所述第二标识为所述目标小区在网络侧的标识。
  23. 根据权利要求14至22中任一项所述的方法，其特征在于，所述方法应用于目标CU或目标CU中的模块或单元。
  24. 一种通信装置，其特征在于，包括用于执行如权利要求1至23中的任一项所述方法的模块或单元。
  25. 一种通信装置，其特征在于，包括处理器和接口电路，所述接口电路用于接收来自所述通信装置之外的其它通信装置的信号并传输至所述处理器或将来自所述处理器的信号发送给所述通信装置之外的其它通信装置，所述处理器通过逻辑电路或执行代码指令用于实现如权利要求1至23中任一项所述的方法。
  26. 一种芯片，其特征在于，包括处理器，所述处理器和存储器耦合，所述存储器用于存储计算机程序，所述处理器用于执行所述存储器中存储的计算机程序以实现如权利要求1至23中任一项所述的方法。
  27. 一种计算机可读存储介质，其特征在于，所述存储介质中存储有计算机程序或指令，当所述计算机程序或指令被通信装置执行时，实现如权利要求1至23中任一项所述的方法。
  28. 一种计算机程序产品，其特征在于，包括计算机程序，当所述计算机程序被运行时，实现如权利要求1至23中任一项所述的方法。
  29. 一种通信系统，其特征在于，包括：
    用于执行如权利要求1至13中任一项所述的方法的源CU、以及与所述源CU交互的源DU；或者，
    用于执行如权利要求1、14至23中任一项所述的方法的目标CU、以及与所述目标CU交互的源DU。
PCT/CN2024/098315 2023-06-15 2024-06-11 一种切换方法和通信装置 Ceased WO2024255719A1 (zh)

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