Communication method and apparatus

Abstract

Provided in the embodiments of the present application are a communication method and apparatus. The method comprises: a terminal device receiving a first switching message from a first access network device, wherein the first switching message is used for instructing the terminal device to switch from a first cell where the terminal device is currently located to a second cell, and the second cell is a cell managed by a second access network device; and on the basis of the first switching message, the terminal device using a key of the first cell to perform first data transmission with the second access network device. By means of the method, the duration of a communication interruption occurring when a terminal device executes cell switching being relatively short can be ensured.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on August 30, 2023, with application number 202311128683.4 and application name “A Communication Method and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0004] In mobile communication systems, the communication link between a terminal and the access network changes due to terminal movement. Based on the terminal's movement, the access network instructs the terminal to switch cells. The handover process from the source cell to the target cell may cause a period of interruption, impacting the user experience.

[0005] The current solution to this problem is for the terminal device to maintain communication with the source and target base stations via two separate communication links, each using a dual-active protocol stack. However, this solution is complex to implement, requires high hardware requirements, and is costly to implement. Therefore, achieving minimal disruption to terminal devices during cell handover (or base station handover) with minimal complexity and hardware cost is a pressing issue.

[0006] Summary of the Invention

[0007] The present application proposes a communication method and apparatus, which can ensure that the duration of communication interruption during cell switching of a terminal device is short.

[0008] In a first aspect, the present application provides a communication method, which can be executed by a terminal device or by a chip corresponding to the terminal device, without limitation. The method may specifically include: receiving a first switching message from a first access network device, the first switching message being used to instruct the terminal device to switch from a first cell currently located to a second cell, the second cell being a cell under the jurisdiction of the second access network device; and based on the first switching message, performing first data transmission with the second access network device using a secret key of the first cell.

[0009] In the embodiment of the present application, the first cell refers to the cell that the terminal device is currently connected to, and the terminal device communicates with the first access network device (e.g., a base station) through the first cell. The second cell is a cell that the terminal device is not currently connected to but is about to access, and the terminal device can communicate with the second access network device by accessing the second cell. In the above, the secret key of the first cell is deduced based on the configuration information of the secret key of the first cell.

[0010] In the present application scheme, when the terminal device receives a first switching message from the first access network device to instruct the terminal device to switch from the first cell where it is currently located to the second cell, the terminal device can still use the secret key of the first cell to transmit data with the second access network device, thereby ensuring that the duration of communication interruption when the terminal device performs cell switching is relatively short.

[0011] In a possible implementation, the first handover message includes cell configuration indication information, where the cell configuration indication information is used to indicate that the second cell uses the same configuration information as that of the first cell.

[0012] Through this implementation, the configuration information used by the second cell to be switched is indicated to the terminal device as being the same as the configuration information of the first cell where the terminal device is currently located. Then the terminal device can quickly and accurately communicate with the second cell with reference to the configuration information of the first cell.

[0013] In one possible implementation, the terminal device uses the secret key of the first cell to perform first data transmission with the second access network device, including: when a communication connection is established with the second cell and the secret key of the second cell is not deduced, using the secret key of the first cell to perform first data transmission with the second access network device.

[0014] Through this implementation, it is possible to ensure that the terminal device effectively communicates with the second cell and effectively reduce the duration of communication interruption when the terminal device performs cell switching.

[0015] In one possible implementation, the terminal device uses the secret key of the first cell to perform first data transmission with the second access network device, including: using the secret key of the first cell to encrypt and integrity protect the uplink data to obtain uplink first data; sending the uplink first data to the second access network device; and / or receiving downlink first data from the second access network device, and using the secret key of the first cell to decrypt and integrity check the downlink first data.

[0016] Through this implementation, the terminal device can use the key of the first cell to perform effective uplink and / or downlink data transmission with the second access network device.

[0017] In a possible implementation, after the terminal device establishes a communication connection with the second cell, the method further includes: receiving configuration information of the secret key of the second cell from the second access network device.

[0018] Through this implementation, the terminal device can effectively deduce the secret key of the second cell by using the configuration information of the secret key of the second cell.

[0019] In a possible implementation, the method also includes: the terminal device identifies the first data through a first target identifier, and the first target identifier can be but is not limited to: an identifier of a first bearer, or an identifier of a first logical channel, or a first identifier carried in the first data; wherein the first identifier can be used to indicate which data belongs to the first data; the first bearer or the first logical channel is used to transmit the first data.

[0020] Through this implementation, the terminal device can effectively and accurately identify that the data from the second access network device is the first data, and then can accurately use the key of the first cell to process the first data.

[0021] In one possible implementation, after the terminal device derives the secret key of the second cell, the method further includes: the terminal device uses the secret key of the second cell to encrypt and integrity protect the uplink data to obtain uplink second data; sends the uplink second data to the second access network device; and / or receives downlink second data from the second access network device, and uses the secret key of the second cell to decrypt and integrity check the downlink second data.

[0022] Through this implementation, after deducing the secret key of the second cell, the terminal device can effectively use the secret key of the second cell to perform data transmission with the second access network device.

[0023] In one possible implementation, the method also includes: the terminal device can identify the second data through a second target identifier, and the second target identifier can be but is not limited to: an identifier of a second bearer, or a second logical channel identifier, or a second identifier carried in the second data, wherein the second identifier can be used to indicate which data belongs to the second data; the second bearer or the second logical channel is used to transmit the second data.

[0024] Through this implementation, the terminal device can effectively and accurately identify that the data from the second access network device is the second data, and can then accurately use the secret key of the second cell to process the second data.

[0025] In one possible implementation, the method also includes: the terminal device receives a first indication message from the second access network device, and the first indication message is used to instruct the terminal device to perform one or more of the following: stop using the key of the first cell to process data, delete the key of the first cell, stop processing associated with the key of the first cell, release the first bearer or first logical channel of the first data, and stop carrying the second identifier in the second data.

[0026] Through this implementation, the terminal device can stop using the secret key of the first cell and stop communicating with the first cell.

[0027] In a second aspect, the present application provides a communication method, which can be executed by a first access network device or by a chip corresponding to the first access network device, without limitation. The method can specifically include: sending a first switching message to a terminal device, the first switching message being used to instruct the terminal device to switch from a first cell currently located to a second cell, the second cell being a cell under the jurisdiction of a second access network device; and using a secret key of the first cell to perform first data transmission with the second access network device.

[0028] In the embodiment of the present application, the first cell refers to the cell that the terminal device is currently connected to, and the terminal device communicates with the first access network device (e.g., a base station) through the first cell. The second cell is a cell that the terminal device is not currently connected to but is about to access, and the terminal device can communicate with the second access network device by accessing the second cell. In the above, the secret key of the first cell is deduced based on the configuration information of the secret key of the first cell.

[0029] In the present application scheme, when the first access network device instructs the terminal device to switch from the current first cell to the second cell, the first access network device can use the secret key of the first cell to perform the first data transmission with the second access network device. Correspondingly, the terminal device side can also use the secret key of the first cell to perform the first data transmission with the second access network device, which is equivalent to the first access network device and the terminal device can use the second access network device to perform the first data transmission, thereby ensuring that the terminal device has a short communication interruption time when performing cell switching.

[0030] In one possible implementation, before the first access network device sends a first switching message to the terminal device, the method further includes: sending a first switching request message to the second access network device, the first switching request message including the address information of the user plane tunnel of the first access network device; receiving a first switching response message from the second access network device, the first switching response message including the address information of the user plane tunnel of the second access network device.

[0031] Through this implementation, accurate and effective data transmission between the first access network device and the second access network device can be ensured.

[0032] In one possible implementation, the first switching request information also includes third indication information, and the third indication information is used to request the second cell to use the configuration information of the first cell; the first switching response information is used to indicate that the second cell confirms the use of the configuration information of the first cell; wherein the configuration information of the first cell includes the uplink physical layer channel configuration information of the first cell and the downlink physical layer channel configuration information of the first cell.

[0033] Through this implementation, the second cell can effectively use the same configuration information as the first cell, so that subsequent terminal devices can quickly and accurately access the second cell.

[0034] In one possible implementation, before the first access network device uses the secret key of the first cell to perform first data transmission with the second access network device, the method also includes: receiving a first response message from the terminal device, the first response message being used to notify the terminal device to confirm switching from the first cell to the second cell; using the secret key of the first cell to perform first data transmission with the second access network device, including: using the secret key of the first cell to encrypt and integrity protect the downlink data to obtain downlink first data; sending the downlink first data to the second access network device according to the address information of the user plane tunnel of the second access network device; and / or receiving uplink first data from the second access network device, and using the secret key of the first cell to decrypt and integrity check the uplink first data to obtain uplink data.

[0035] Through this implementation, after the terminal device confirms switching from the first cell to the second cell, the first access network device uses the key of the first cell to perform effective uplink and / or downlink first data transmission with the second access network device.

[0036] In one possible implementation, the method further includes: the first access network device receives second indication information from the second access network device, the second indication information being used to instruct the first cell or the first access network device to stop generating or sending the first data and to release the first bearer or first logical channel of the first data; and sends first status information to the second access network device, the first status information being used to indicate identification information of the first data that has been successfully sent and / or unsuccessfully sent.

[0037] Through this implementation, the first access network device no longer uses the key of the first cell to process data and stops communication with the first cell. At the same time, the first access network device can also feedback identification information of the first data that has been successfully sent / or unsuccessfully sent to the second access network device.

[0038] In a possible implementation manner, the method further includes: the first access network device sending third data to the second access network device, where the third data is the unsuccessfully sent, unencrypted and integrity-protected data.

[0039] Through this implementation, the first access network device can continue to transmit the unsuccessfully sent data to the terminal device through the second access network device.

[0040] In a possible implementation, the method also includes: the first access network device can identify the first data through a first target identifier, and the first target identifier can be but is not limited to: an identifier of a first bearer, or an identifier of a first logical channel, or a first identifier carried in the first data, wherein the first identifier can be used to indicate which data belongs to the first data; the first bearer or the first logical channel is used to transmit the first data.

[0041] Through this implementation, the first access network device can effectively and accurately identify that the data from the second access network device is the first data, and can then accurately use the key of the first cell to process the first data.

[0042] In a third aspect, the present application provides a communication method, which can be executed by a second access network device or a chip corresponding to the second access network device, without limitation. The method may specifically include: receiving first downlink data from a first access network device, and sending the first downlink data to a terminal device; and / or receiving first uplink data from the terminal device, and sending the first uplink data to the first access network device; wherein the first data is encrypted and integrity protected using the key of the first cell.

[0043] In the embodiment of the present application, the first cell refers to the cell that the terminal device is currently connected to, and the terminal device communicates with the first access network device (e.g., a base station) through the first cell. The second cell is a cell that the terminal device is not currently connected to but is about to access, and the terminal device can communicate with the second access network device by accessing the second cell. In the above, the secret key of the first cell is deduced based on the configuration information of the secret key of the first cell.

[0044] In the solution of the present application, the second access network device can assist the terminal device in performing uplink and / or downlink first data transmission with the first access network device to reduce the duration of communication interruption when the terminal device performs cell switching.

[0045] In one possible implementation, the method further includes: the second access network device receives a first switching request message from the first access network device, the first switching request message including the address information of the user plane tunnel of the first access network device; the second access network device sends a first switching response message to the first access network device, the first switching response message including the address information of the user plane tunnel of the second access network device.

[0046] Through this implementation, accurate and effective data transmission between the second access network device and the first access network device can be ensured.

[0047] In one possible implementation, the first switching request information also includes third indication information, and the third indication information is used to request the second cell to use the configuration information of the first cell, and the first switching response information is used to indicate that the second cell confirms the use of the configuration information of the first cell; wherein the configuration information of the first cell includes the uplink physical layer channel configuration information of the first cell and the downlink physical layer channel configuration information of the first cell.

[0048] Through this implementation, the second cell and the first cell can effectively use the same configuration information, so that subsequent terminal devices can quickly and accurately access the second cell.

[0049] In a possible implementation, the second access network device sends the uplink first data to the first access network device, including: sending the uplink first data to the first access network device according to address information of the user plane tunnel of the first access network device.

[0050] Through this implementation, the second access network device can effectively and accurately send the uplink first data to the first access network device.

[0051] In one possible implementation, the method further includes: the second access network device receives uplink second data from the terminal device; uses the secret key of the second cell to decrypt and integrity check the uplink second data to obtain uplink data; sends the uplink data to the user plane function network element in the core network device; and / or receives downlink data from the user plane function network element in the core network device and / or the first access network device; uses the secret key of the second cell to encrypt and integrity protect the downlink data to obtain downlink second data; and sends the downlink second data to the terminal device.

[0052] In the above description, the downlink data received by the second access network device from the first access network device may be data that the first access network device has not successfully sent to the terminal device.

[0053] Through this implementation, the second access network device can effectively and flexibly use the secret key of the second cell to process data from the terminal device, data from the core network device, and data from the first access network device, and perform corresponding data transmission.

[0054] In one possible implementation, the method further includes: after the first event, the second access network device sends a path switching request message to the access and mobility management function network element in the core network device; the path switching request message is used to request that the data transmission path be switched from a first path corresponding to the user plane function network element and the first access network device to a second path corresponding to the user plane function network element and the second access network device; the first event may be, but is not limited to, any one of the following:

[0055] (1) receiving the downlink first data from the first access network device; (2) receiving the uplink first data from the terminal device; (3) receiving the uplink second data from the terminal device.

[0056] Through this implementation, when the terminal device communicates, the second access network device can be flexibly triggered to request the access and mobility management function network element in the core network to switch the path for transmitting data between the user function network element in the core network and the access network device.

[0057] In one possible implementation, the method further includes: the second access network device receives a path switching response message from the access and mobility management function network element, and obtains the configuration information of the secret key of the second cell in the path switching response message; the path switching response message is used to indicate that the data transmission path has been switched from the first path to the second path.

[0058] Through this implementation, the second access network device can effectively obtain the configuration information of the second cell's key from the access and mobility management function network element in the core network, and then the second access network device can use the configuration information of the second cell's key to deduce the second cell's key. The second access network device can also transmit the configuration information of the second cell's key to the terminal device, so that the terminal device can effectively deduce the second cell's key.

[0059] In one possible implementation, the method further includes: the second access network device sends a first indication message to the terminal device, and sends a second indication message to the first access network device; wherein the first indication message is used to instruct the terminal device to perform one or more of the following: stop using the key of the first cell to process data, delete the key of the first cell, stop processing associated with the key of the first cell, release the first bearer or first logical channel of the first data, and stop carrying the second identifier in the second data; the second indication message is used to instruct the first cell or the first access network device to stop generating or sending the first data and release the first bearer or first logical channel of the first data.

[0060] Through this implementation, the terminal device and the first access network device (or first cell) stop processing operations associated with the key of the first cell, and no longer use the key of the first cell to process data and communications.

[0061] In a possible implementation, the method further includes: the second access network device receiving first status information from the first access network device, where the first status information is used to indicate identification information (eg, a serial number) of the first data that has been successfully sent and / or unsuccessfully sent.

[0062] Through this implementation, the second access network device is informed of the first data that has been successfully sent and / or unsuccessfully sent by the first access network device.

[0063] In a possible implementation manner, the method further includes: the second access network device receiving third data from the first access network device, where the third data is the unsuccessfully sent unencrypted and integrity-protected data.

[0064] Through this implementation, the second access network device can continue to send the data that the first access network device failed to send to the terminal device.

[0065] In one possible embodiment, the method also includes: the second access network device identifies the first data through a first target identifier, and the first target identifier may be but is not limited to: an identifier of a first bearer, or an identifier of a first logical channel, or a first identifier carried in the first data; the first bearer or the first logical channel is used to transmit the first data; the second access network device identifies the second data through a second target identifier, and the second target identifier may be but is not limited to: an identifier of a second bearer, or an identifier of a second logical channel, or a first identifier carried in the second data; the second bearer or the second logical channel is used to transmit the second data.

[0066] Through this implementation, the second access network device can effectively and accurately identify the first data and the second data, and then for the first data and the second data, the second access network device can accurately determine the sending object for transmission.

[0067] In a fourth aspect, an embodiment of the present application also provides a communication device, which can be used to execute the method of the first aspect. The device can be a terminal device, or the device can be a component in the terminal device (for example, a chip, or a chip system, or a circuit), or it can be a device that can be used in conjunction with the terminal device.

[0068] In one possible implementation, the device may include a module or unit corresponding to each of the methods / operations / steps / actions described in the first aspect. The module or unit may be a hardware circuit, software, or a combination of a hardware circuit and software. In one possible implementation, the device may include a processing unit (also referred to as a processing module) and a communication unit (also referred to as a communication module), wherein the communication unit may be used to perform the functions of receiving and / or sending, and the processing unit may be used to perform the method described in the first aspect or any possible implementation of the first aspect.

[0069] In the fifth aspect, an embodiment of the present application also provides a communication device, which can be used to execute the method of the second aspect. The device can be a first access network device, or the device can be a component in the first access network device (for example, a chip, or a chip system, or a circuit), or it can be a device that can be used in combination with the first access network device.

[0070] In one possible implementation, the device may include a module or unit corresponding to each of the methods / operations / steps / actions described in the second aspect. The module or unit may be a hardware circuit, software, or a combination of a hardware circuit and software. In one possible implementation, the device may include a processing unit (also referred to as a processing module) and a communication unit (also referred to as a communication module), wherein the communication unit may be used to perform the functions of receiving and / or sending, and the processing unit may be used to perform the method described in the second aspect or any possible implementation of the second aspect.

[0071] In the sixth aspect, an embodiment of the present application also provides a communication device, which can be used to execute the method of the third aspect. The device can be a second access network device, or the device can be a component in the second access network device (for example, a chip, or a chip system, or a circuit), or it can be a device that can be used in combination with the second access network device.

[0072] In one possible implementation, the device may include a module or unit corresponding to each of the methods / operations / steps / actions described in the third aspect. The module or unit may be a hardware circuit, software, or a combination of a hardware circuit and software. In one possible implementation, the device may include a processing unit (also referred to as a processing module) and a communication unit (also referred to as a communication module), wherein the communication unit may be used to perform the functions of receiving and / or sending, and the processing unit may be used to perform the method described in the third aspect or any possible implementation of the third aspect.

[0073] In the seventh aspect, an embodiment of the present application provides a device, which includes: at least one processor and a communication interface; wherein the communication interface is used to communicate with other devices; the processor is used to run a set of programs so that the device can implement the method provided in the above-mentioned first aspect or any possible implementation method thereof.

[0074] In the eighth aspect, an embodiment of the present application provides a device, which includes: at least one processor and a communication interface; wherein the communication interface is used to communicate with other devices; the processor is used to run a set of programs so that the device can implement the method provided in the above-mentioned second aspect or any possible implementation method thereof.

[0075] In the ninth aspect, an embodiment of the present application provides a device, which includes: at least one processor and a communication interface; wherein the communication interface is used to communicate with other devices; the processor is used to run a set of programs so that the device can implement the method provided in the above-mentioned third aspect or any possible implementation method thereof.

[0076] In the tenth aspect, an embodiment of the present application also provides a computer storage medium, which stores a software program. When the software program is read and executed by one or more processors, it can implement the method provided by the above-mentioned first aspect or any possible implementation method thereof, or implement the method provided by the above-mentioned second aspect or any possible implementation method thereof, or implement the method provided by the above-mentioned third aspect or any possible implementation method thereof.

[0077] In the eleventh aspect, an embodiment of the present application also provides a computer program product comprising instructions, which, when run on a computer, enables the execution of the method provided in the above-mentioned first aspect or any possible implementation thereof, or enables the execution of the method provided in the above-mentioned second aspect or any possible implementation thereof, or enables the execution of the method provided in the above-mentioned third aspect or any possible implementation thereof.

[0078] In the twelfth aspect, an embodiment of the present application provides a communication system, including a terminal device capable of implementing the method provided in the first aspect above, a first access network device capable of implementing the method provided in the second aspect above, and a second access network device capable of implementing the method provided in the third aspect above.

[0079] In the thirteenth aspect, an embodiment of the present application also provides a chip system, which includes a processor for supporting a terminal device to implement the functions involved in the above-mentioned first aspect; or for supporting a first access network device to implement the functions involved in the above-mentioned second aspect; or for supporting a second access network device to implement the functions involved in the above-mentioned third aspect.

[0080] In one possible design, the chip system further includes a memory for storing necessary program instructions and data for execution by the loading device. The chip system can be composed of a chip or include a chip and other discrete devices.

[0081] It should be noted that the technical effects that can be achieved by any possible implementation method of the above-mentioned fourth to thirteenth aspects or the fourth to thirteenth aspects can be correspondingly described with reference to the technical effects that can be achieved by any possible implementation method of the above-mentioned first to third aspects or the first to third aspects; they will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] FIG1A is a schematic diagram of a mobile communication system to which embodiments of the present application may be applied;

[0083] FIG1B is a schematic diagram of a network architecture applicable to embodiments of the present application;

[0084] FIG2 is a schematic structural diagram of a distributed base station provided in an embodiment of the present application;

[0085] FIG3 is a flow chart of a communication method provided in an embodiment of the present application;

[0086] FIG4 is a specific flow chart of the first embodiment provided in the embodiments of the present application;

[0087] FIG5 is a specific flow chart of a second embodiment provided in the embodiments of the present application;

[0088] FIG6A is a schematic diagram of a downlink transmission path provided in an embodiment of the present application;

[0089] FIG6B is a schematic diagram of a downlink transmission path provided in an embodiment of the present application;

[0090] FIG7 is a specific flow chart of a third embodiment provided in the embodiments of the present application;

[0091] FIG8 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0092] FIG9 is a schematic structural diagram of another communication device provided in an embodiment of the present application;

[0093] FIG10 is a schematic diagram of the structure of a chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0094] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of", "said", "above", "the" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context. It should also be understood that in the embodiments of the present application, "one or more" refers to one, two or more; "and / or" describes the association relationship of associated objects, indicating that three relationships may exist; for example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0095] References to "one embodiment" or "some embodiments" described in this specification mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. The terms "including", "comprising", "having" and their variations involved in this application all mean "including but not limited to", unless otherwise specifically emphasized. Words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions, and any embodiment or design described as "exemplary" or "for example" should not be interpreted as being more preferred or more advantageous than other embodiments or designs. The use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0096] The multiple involved in the embodiments of the present application refers to greater than or equal to two. It should be noted that in the description of the embodiments of the present application, words such as "first" and "second", or numbers such as "1" and "2", are only used to distinguish the purpose of description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. In addition, the term "used for indication" mentioned in the description of the embodiments of the present application can include being used for direct indication and being used for indirect indication. When describing a certain indication information as being used to indicate A, it can include that the indication information directly indicates A or indirectly indicates A, and it does not mean that the indication information must carry A.

[0097] The term "switching" as used in the embodiments of this application can be understood as updating, replacing, or changing. For example, a UE's path switching can refer to updating or replacing the UE's original path with the new path after determining the UE's new path, so that the UE can communicate via the new path. Therefore, the term "switching" can also be replaced with "updating" or other terms, and this application does not limit this.

[0098] In order to better understand the embodiments of the present application, the following first introduces the application scenarios and existing problems of the embodiments of the present application. It should be noted that the application scenarios are intended to make the embodiments of the present application easier to understand and should not be regarded as limiting the scope of protection claimed by the present application.

[0099] In a mobile communication system, the movement of a terminal causes changes in the communication link between the terminal device and the access network device. Based on the terminal device's movement, the access network device instructs the terminal device to perform a cell handover. During the handover process from a source cell to a target cell, the terminal device must encrypt data and signaling using the target base station's new key before communicating with the target base station. Because the secure encryption function resides at the packet data convergence protocol (PDCP) layer, upon receiving the handover command, the terminal device must derive the new key and re-establish the PDCP. This processing time can cause communication interruption during the handover process, impacting the user experience.

[0100] In view of the above problems, the present application provides a communication method, which can ensure that the duration of communication interruption when the terminal device performs cell switching is short.

[0101] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as wideband code division multiple access (WCDMA) system, general packet radio service (GPRS), long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD), universal mobile telecommunication system (UMTS), world-wide interoperability for microwave access (WiMAX) communication system, fifth generation (5G) system or future sixth generation communication system, etc.

[0102] Figure 1A is a schematic diagram of a communication system architecture applicable to embodiments of the present application. As shown in Figure 1A , the communication system includes a wireless access network 100 and a core network 200. Optionally, the communication system may also include the Internet 300. The wireless access network 100 may include at least one access network device (such as 110a and 110b in Figure 1A ) and at least one terminal (such as 120a-120j in Figure 1A ). The terminal is wirelessly connected to the access network device, and the access network device is wirelessly or wiredly connected to the core network. The core network device and the access network device may be independent, distinct physical devices, or the functions of the core network device and the logical functions of the access network device may be integrated into the same physical device, or a single physical device may integrate some of the functions of the core network device and some of the functions of the access network device. Terminals and access network devices may be interconnected via wired or wireless connections. Figure 1A is merely a schematic diagram. The communication system may also include other network devices, such as wireless relay devices and wireless backhaul devices, which are not shown in Figure 1A .

[0103] Referring to FIG1B , the core network equipment includes a session management network element, an access management network element, a user plane function network element, and the like.

[0104] Among them, the session management network element is mainly used for session management, allocation and management of Internet Protocol (IP) addresses of terminal devices, selection of endpoints for manageable user equipment plane functions, policy control, or charging function interfaces, and downlink data notification. In 5G communications, the session management network element can be a session management function (SMF) network element. In future communications such as 6G communications, the session management function network element can still be an SMF network element or have other names, which are not limited in this application. Nsmf is a service-based interface provided by SMF. SMF can communicate with other network functions through Nsmf.

[0105] Access management network element: mainly used for mobility management and access management, etc. For example, it can be the mobility management entity (MME) function in the 4G communication network or the access and mobility management function (AMF) network element in the 5G network. In future communications such as 6G communications, the access management network element can still be an AMF network element, or have other names, which are not limited in this application. Namf is a service-based interface provided by AMF, and AMF can communicate with other network functions through Namf.

[0106] User plane function network element: used for packet routing and forwarding, or quality of service (QoS) processing of user plane data. In 5G communications, the user plane network element can be a user plane function (UPF) network element. In future communications such as 6G communications, the user plane network element can still be a UPF network element, or have other names, which are not limited by this application. Figure 1B above is only an example of a network architecture that can be adapted by the embodiments of this application, which also includes other network elements (or devices). For detailed introduction, please refer to existing technologies and will not be described in detail here.

[0107] The access network device can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) in a fifth generation (5G) mobile communication system, a base station in a sixth generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a wireless fidelity (WiFi) system, etc.; it can also be a module or unit that completes part of the functions of a base station, for example, a centralized unit (CU) or a distributed unit (DU). The access network device can be a macro base station, a micro base station or an indoor station, a relay node or a donor node, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the access network device. In the embodiments of the present application, a base station is used as an example of an access network device for description.

[0108] In one possible implementation, some access network equipment functions are deployed in a CU, while the remaining functions are deployed in a DU. Multiple DUs can share or connect to a single CU, saving costs and facilitating network expansion. The CU and DU can be divided based on protocol stacks. One possible approach is to deploy the radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) layers in the CU, while the remaining radio link control (RLC), medium access control (MAC), and physical layers (PHY) are deployed in the DU. The CU and DU are connected via the F1 interface. The CU represents the gNB, connecting to the core network via the NG interface. The CU represents the gNB, connecting to other gNBs via the Xn interface. The CU can also represent the gNB, connecting to other eNBs via the X2 interface, performing dual connectivity. This is shown in Figure 2 below. Furthermore, the CU comprises the central unit control plane (CU-CP) and the central unit user plane (CU-UP). CU-UP and CU-CP can be on the same physical device or on different physical devices. CU-CP and CU-UP are connected through an interface (for example, E1 interface). CU-CP represents the base station and is connected to the core network through an interface (for example, Ng interface). CU-CP is connected to DU through an interface (for example, F1-C interface), and CU-UP is connected to DU through an interface (for example, F1-U interface). The number of CU-CPs can be one, and the number of CU-UPs can be one or more. Multiple CU-UPs can share one CU-CP. CU-CP mainly has control plane functions. CU-UP mainly has user plane functions. One possible implementation method is: for 5G base stations, the RRC layer can be deployed on the CU-CP, while the SDAP layer is not deployed on the CU-CP. CU-CP can also have some control plane functions of the PDCP layer, such as processing signaling radio bearers (SRBs). The SDAP layer can be deployed on the CU-UP, but the RRC layer is not deployed on the CU-UP. The CU-UP may also have user plane functions of the PDCP layer, such as processing data radio bearers (DRBs).

[0109] It should be noted that in different systems, CU (or CU-CP and CU-UP), or DU may have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (O-RAN) system, CU may also be referred to as O-CU (open CU), DU may also be referred to as O-DU, CU-CP may also be referred to as O-CU-CP, CU-UP may also be referred to as O-CU-UP, and RU may also be referred to as O-RU. For the sake of convenience of description, this application uses CU, CU-CP, CU-UP, DU and RU as examples for description. Any of the CU (or CU-CP and 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.

[0110] A terminal may also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. The terminal can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. The terminal can be a mobile phone, tablet computer, computer with wireless transceiver function, wearable device, vehicle, drone, helicopter, airplane, ship, robot, robotic arm, smart home device, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal device.

[0111] The access network equipment and UE can be fixed or movable. The access network equipment and UE can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on the water surface; they can also be deployed on airplanes, balloons and artificial satellites in the air, and the embodiments of the present application are not limited to this. In addition, the access network equipment and UE, the access network equipment and the access network equipment, and the UE and the UE can communicate through the authorized spectrum, or through the unauthorized spectrum, or through the authorized spectrum and the unauthorized spectrum at the same time; they can communicate through the spectrum below 6 gigahertz (GHz), or through the spectrum above 6 GHz, and can also use the spectrum below 6 GHz and the spectrum above 6 GHz at the same time. The embodiments of the present application do not limit the spectrum resources used for wireless communications.

[0112] In the embodiments of the present application, the functions of the access network device may also be performed by a module (such as a chip) in the access network device, or by a control subsystem that includes the functions of the access network device. The control subsystem that includes the functions of the access network device here may be a control center in the above-mentioned application scenarios such as smart grid, industrial control, smart transportation, and smart city. The functions of the terminal device may also be performed by a module (such as a chip or modem) in the terminal device, or by a device that includes the functions of the terminal device.

[0113] In this application, the access network device sends downlink signals / information / data to the terminal device. The downlink information / data can be carried on, but not limited to, downlink channels. The terminal device sends uplink signals / information / data to the access network device. The uplink information / data can be carried on, but not limited to, uplink channels. In order to communicate with the access network device, the terminal device needs to establish a wireless connection with the cell under the jurisdiction (control) of the access network device. The cell with which the terminal device has established a wireless connection is called the serving cell of the terminal device.

[0114] The technical solution of this application is introduced below in conjunction with specific embodiments.

[0115] The embodiment of the present application provides a communication method, which is applicable to but not limited to the communication system shown in Figures 1A and 1B. The method can be performed by a terminal device, a first access network device, and a second access network device; or the method can be performed by components (modules, chips, etc.) corresponding to the terminal device, the first access network device, and the second access network device; or the method can be performed by a device corresponding to the terminal device, the first access network device, and the second access network device. The embodiment of the present application does not specifically limit the specific form and quantity corresponding to the terminal device, the first access network device, and the second access network device. Please refer to Figure 3. The specific process of the method is as follows:

[0116] S301: A first access network device sends a first handover message to a terminal device, the first handover message being used to instruct the terminal device to handover from a first cell currently located to a second cell, where the second cell is a cell under the jurisdiction of the second access network device. Accordingly, the terminal device receives the first handover message from the first access network device.

[0117] In the embodiment of the present application, the first cell refers to the cell that the terminal device is currently connected to, and the terminal device communicates with the first access network device (e.g., a base station) through the first cell. The second cell is a cell that the terminal device is not currently connected to but is about to access, and the terminal device can communicate with the second access network device by accessing the second cell.

[0118] Optionally, the first handover message includes cell configuration indication information, where the cell configuration indication information is used to indicate that the second cell uses the same configuration information as the first cell (ie, the configuration information of the first cell).

[0119] In one embodiment, before the first access network device sends the first handover message to the terminal device, the first access network device further includes: sending a first handover request message to the second access network device, where the first handover request message includes the address information of the user plane tunnel of the first access network device. In this way, the second access network device can obtain the address information of the user plane tunnel of the first access network device by receiving the first handover request message, so that it can subsequently accurately transmit data with the first access network device based on the address information of the user plane tunnel of the first access network device.

[0120] Accordingly, after receiving the first handover request information, the second access network device sends a first handover response information to the first access network device. The first handover response information includes the address information of the user plane tunnel of the second access network device. In this way, the first access network device can obtain the address information of the user plane tunnel of the second access network device through the received first handover response information, so that it can subsequently accurately transmit data with the second access network device based on the address information of the user plane tunnel of the second access network device.

[0121] In an embodiment of the present application, the address information of the user plane tunnel of the first access network device or the second access network device may include address information of an uplink user plane tunnel and / or address information of a downlink user plane tunnel. Exemplarily, the address information of the user plane tunnel includes a transport layer address and a tunnel endpoint identifier of a General Packet Radio Service GPRS Tunneling Protocol (GPRS Tunneling Protocol, GTP).

[0122] In one embodiment, the first handover request message carries the second cell's key and configuration information for the second cell's key; and the first handover response message fed back by the second access network device to the first access network device also carries the second cell's key configuration information. After receiving the first handover response message, the first access network device includes the second cell's key configuration information in the first handover message and sends it to the terminal device, allowing the terminal device to subsequently deduce the second cell's key. In this embodiment, the first access network device generates the second cell's key configuration information, derives the second cell's key, and then sends the second cell's key and key configuration information to the second access network device for use and transmission in subsequent steps.

[0123] In a possible implementation, the first handover request information further includes third indication information, and the third indication information is used to request the second cell to use the configuration information of the first cell. Accordingly, the first handover response information can be used to instruct the second cell to confirm the use of the configuration information of the first cell. The configuration information of the first cell may include but is not limited to the uplink or downlink physical layer channel configuration information of the first cell. For example, frequency domain bandwidth, cell-radio network temporary identifier (C-RNTI), etc.

[0124] Through the above-mentioned interaction between the first access network device and the second access network device, the second cell and the first cell can use the same configuration information, so that the terminal device can subsequently access the second cell accurately and quickly.

[0125] S302: Based on the first switching message, the terminal device uses the key of the first cell to perform first data transmission with the second access network device.

[0126] In the embodiment of the present application, the secret key of the first cell can be deduced based on the configuration information of the secret key of the first cell.

[0127] In a possible implementation, the terminal device uses the secret key of the first cell to perform first data transmission with the second access network device, which may include: the terminal device uses the secret key of the first cell to perform first data transmission with the second access network device after establishing a communication connection with the second cell and without deducing the secret key of the second cell.

[0128] In a possible implementation, if the first switching request information mentioned above does not carry the key of the second cell and the configuration information of the key of the second cell (that is, the key of the second cell and the configuration information of the key of the second cell are not generated and deduced by the first access network device), then the first switching response information and the first switching message mentioned above will not carry the configuration information of the key of the second cell; in this case, the terminal device can receive the configuration information of the key of the second cell from the second access network device after establishing a communication connection with the second cell; and the configuration information of the key of the second cell can be obtained by the second access network device from the access and mobility management function network element in the core network.

[0129] In an embodiment of the present application, establishing a communication connection between the terminal device and the second cell may include: establishing a bearer (or logical channel) for transmitting first data and a bearer (or logical channel) for transmitting second data between the terminal device and the second cell.

[0130] S303: The first access network device uses the secret key of the first cell to perform first data transmission with the second access network device.

[0131] In one embodiment, before the first access network device uses the secret key of the first cell to perform first data transmission with the second access network device, the method also includes: the first access network device receives a first response message (for example, an RLC ACK message, or a hybrid automatic repeat request (HARQ) acknowledgment (ACK) message, or an RRC message, a media access control MAC control element (CE), etc.) from the terminal device, and the first response message is used to notify the terminal device to confirm the switch from the first cell to the second cell.

[0132] In the embodiment of the present application, the above steps S302 and S303 are the process of exchanging first data between three parties (i.e., the terminal device, the first access network device, and the second access network device). Therefore, the execution order of the steps S302 and S303 is not specifically limited. With respect to the above-mentioned S302, in which the terminal device uses the secret key of the first cell to perform the first data transmission with the second access network device, and S303, in which the first access network device uses the secret key of the first cell to perform the first data transmission with the second access network device, the specific interaction process is as follows:

[0133] Uplink transmission: In step S302, the terminal device uses the secret key of the first cell to encrypt and integrity-protect the uplink data to obtain first uplink data; the first uplink data is sent to the second access network device; accordingly, the second access network device receives the first uplink data from the terminal device. In step S303, the second access network device can send the first uplink data to the first access network device based on the address information of the user plane tunnel of the first access network device; accordingly, after receiving the first uplink data from the second access network device, the first access network device uses the secret key of the first cell to decrypt and integrity-check the first uplink data to obtain the uplink data.

[0134] Downlink transmission: In step S303, the first access network device uses the secret key of the first cell to encrypt and integrity-protect the downlink data to obtain the first downlink data; according to the address information of the user plane tunnel of the second access network device, the first downlink data is sent to the second access network device; in step S302, the second access network device sends the first downlink data to the terminal device, and then the terminal device uses the secret key of the first cell to decrypt and integrity-check the first downlink data to obtain the downlink data.

[0135] In an embodiment of the present application, the terminal device or the first access network device or the second access network device can identify the received first data by a first target identifier, and identify the received second data by a second target identifier. The first target identifier may be, but is not limited to: an identifier of a first bearer, an identifier of a first logical channel, or a first identifier carried in the first data; wherein the first bearer or the first logical channel is used to transmit the first data, and the first identifier is used to indicate which data belongs to the first data. The second target identifier may be, but is not limited to: an identifier of a second bearer, or an identifier of a second logical channel, or a second identifier carried in the second data; wherein the second bearer or the second logical channel is used to transmit the second data, and the second identifier is used to indicate which data belongs to the second data.

[0136] It should be noted that in the embodiment of the present application, after the terminal device establishes a communication connection with the second cell and has not deduced the secret key of the second cell, the above-mentioned uplink transmission and / or downlink transmission can be performed.

[0137] S304: The terminal device uses the secret key of the second cell to perform second data transmission with the second access network device.

[0138] In a possible implementation, the terminal device executes step S304 after deducing the secret key of the second cell.

[0139] In the embodiment of the present application, when the terminal device executes step S304, it may specifically include the following:

[0140] The terminal device uses the secret key of the second cell to encrypt and perform integrity protection processing on the uplink data to obtain uplink second data, and then sends the uplink second data to the second access network device; after receiving the uplink second data from the terminal device, the second access network device uses the secret key of the second cell to decrypt and perform integrity verification processing on the uplink second data to obtain uplink data; further, the second access network device sends the uplink data to the user plane function network element in the core network device; and / or

[0141] The second access network device receives downlink data from the user plane functional network element in the core network device and / or the first access network device, and then uses the secret key of the second cell to encrypt and integrity protect the downlink data to obtain downlink second data; further, the second access network device sends the downlink second data to the terminal device; after the terminal device receives the downlink second data from the second access network device, it can use the secret key of the second cell to decrypt and integrity check the downlink second data.

[0142] In an embodiment of the present application, the terminal device or the second access network device can identify the received second data through a second target identifier, and the second target identifier can be but is not limited to: an identifier of a second bearer, or a second logical channel identifier, or a second identifier carried in the second data; wherein the second bearer or the second logical channel is used to transmit the second data.

[0143] In an embodiment of the present application, the second access network device may send a path switching request message to the access and mobility management function network element in the core network device after the first event; the path switching request message is used to request that the data transmission path be switched from the first path corresponding to the user plane function network element and the first access network device to the second path corresponding to the user plane function network element and the second access network device; wherein the first event may be any one of the following:

[0144] (1) The second access network device receives downlink first data from the first access network device; (2) The second access network device receives uplink first data from the terminal device; (3) The second access network device receives the uplink second data from the terminal device.

[0145] The above (1) and (2) may be steps in the above step S303 in which the terminal device performs the first data transmission with the first access network device through the second access network device.

[0146] In a possible implementation, the method further includes: the second access network device receives a path switching response message from the access and mobility management function network element, and obtains configuration information of the secret key of the second cell in the path switching response message; the path switching response message is used to indicate that the data transmission path has been switched from the first path to the second path.

[0147] After the second access network device receives the configuration information of the secret key of the second cell from the core network device (access and mobility management function network element), it can further send the configuration information of the secret key of the second cell to the terminal device when the terminal device establishes a communication connection with the second cell, so that the terminal device can effectively and accurately deduce the secret key of the second cell based on the configuration information of the secret key of the second cell.

[0148] In one embodiment, after receiving the path switching response information, the second access network device further performs: sending first indication information to the terminal device, and sending second indication information to the first access network device.

[0149] In the above, the first indication information is used to instruct the terminal device to execute but not limited to: stop using the key of the first cell to process data, delete the key of the first cell, stop processing associated with the key of the first cell, release the first bearer or first logical channel of the first data, and stop carrying the second identifier in the second data.

[0150] The second indication information is used to instruct the first cell or the first access network device to stop generating or sending the first data and release the first bearer or first logical channel of the first data.

[0151] In addition, optionally, after receiving the second indication information sent by the second access network device, the first access network device sends first status information to the second access network device, and the first status information is used to indicate identification information of the first data that has been successfully sent and / or unsuccessfully sent, such as a serial number.

[0152] Optionally, the first access network device further sends third data to the second access network device, where the third data is the unencrypted and integrity-protected data that was not successfully sent.

[0153] In an embodiment of the present application, the payload of the third data may be the same as the payload of the first data that was previously sent by the first access network device but was not successfully received by the terminal device.

[0154] In an embodiment of the present application, the above-mentioned first data may refer to data obtained after encryption and integrity protection processing using the secret key of the first cell, and the second data may refer to data obtained after encryption and integrity protection processing using the secret key of the second cell. In other embodiments or application scenarios, the first data may also refer to data obtained after processing using other private information associated with the first cell, and the second data may also refer to data obtained after processing using other private information associated with the second cell. In this case, the "secret key of the first cell" in the full text can be replaced with other private information associated with the first cell, and the "secret key of the second cell" can be replaced with other private information associated with the second cell. The process of key deduction can be implemented by referring to the deduction process of "secret key of the first cell" and "secret key of the second cell".

[0155] An embodiment of the present application provides a communication method and apparatus, the method comprising: a terminal device receiving a first handover message from a first access network device, the first handover message being used to instruct the terminal device to handover from a first cell currently located to a second cell, the second cell being a cell under the jurisdiction of the second access network device; and the terminal device, based on the first handover message, using a secret key of the first cell to perform first data transmission with the second access network device. This method can ensure that the duration of communication interruption experienced by the terminal device during cell handover is short, or in other words, can reduce the duration of communication interruption experienced by the terminal device during cell handover.

[0156] Based on the communication method shown in FIG3 , several specific embodiments are further described below.

[0157] Example 1:

[0158] In the first embodiment, for the scenario where the UE switches base stations (or the UE switches cells), taking UE1 as an example, UE1 switches from the source base station S-gNB (which can also be the source cell) to the target base station T-gNB (which can also be the target cell). Before UE1 switches, the user data exchanged between the UPF and UE1 (that is, UE1 sends user data to the UPF, and the UPF sends user data to UE1) is forwarded via the source base station (S-gNB); after UE1 switches, the user data exchanged between the UPF and UE1 is forwarded via the target base station (T-gNB). This first embodiment mainly introduces the communication during the switching process of UE1. As shown in Figure 4, the process of this first embodiment is as follows:

[0159] S401: The S-gNB sends a handover request message to the T-gNB.

[0160] Accordingly, the T-gNB receives the handover request message from the S-gNB. The handover request message includes the address information of the S-gNB's uplink user plane tunnel. This allows the T-gNB to subsequently send uplink data to the S-gNB based on the address information of the S-gNB's uplink user plane tunnel. Furthermore, the handover request message includes the target cell's key parameters, such as the next-hop chain calculation value. The handover request message also includes the target cell's key, which is derived by the S-gNB based on the target cell's key parameters.

[0161] The handover request message may also be referred to as a handover preparation message, which is used to request the configuration information of the target cell from the T-gNB.

[0162] Optionally, the handover request message may further include first configuration information of the source cell, and request the target cell to use configuration information that is the same as the first configuration information.

[0163] Exemplarily, the handover request message is used to request the target cell to use the same physical layer channel configuration information (i.e., uplink physical layer channel configuration information and downlink physical layer channel configuration information) as the source cell, such as frequency domain bandwidth, cell radio network temporary identifier C-RNTI, etc.

[0164] In the embodiment of the present application, the first configuration information refers to various configuration information that can be reused by UE1 in different cells (such as the source cell and the target cell), including but not limited to the above-mentioned physical channel configuration information. However, the source cell and the target cell generally cannot use the same cell identifier or key, and therefore, such information does not fall within the scope of the first configuration information.

[0165] In the above example, the source cell is managed (or governed / controlled) by the S-gNB. UE1 is currently connected to the source cell and is communicating with the S-gNB through the source cell. The target cell is managed (or governed / controlled) by the T-gNB. At this point, UE1 has not yet connected to the target cell and will subsequently communicate with the T-gNB through the target cell.

[0166] In this embodiment of the present application, when UE1 switches base stations (or cells), if the S-gNB has pre-provided multiple candidate cells and configuration information of these multiple candidate cells to UE1, then the target cell can be one of these multiple candidate cells. If the S-gNB has not pre-provided multiple candidate cells to UE1, then the target cell is a cell temporarily determined by the S-gNB for UE1 to be accessible. Therefore, this embodiment is applicable to both scenarios where multiple candidate cells are pre-configured for UE1 and scenarios where multiple candidate cells are not pre-configured for UE1.

[0167] S402: The T-gNB sends a handover request response message to the S-gNB.

[0168] Accordingly, the S-gNB receives the handover request response message from the T-gNB. The handover request response message includes the address information of the downlink user plane tunnel of the T-gNB. In this way, the S-gNB can subsequently send downlink data to the T-gNB based on the address information of the downlink user plane tunnel of the T-gNB.

[0169] Exemplarily, the address information of the user plane tunnel in the above S401 and S402 can be Xn-U user plane tunnel address information or F1-U user plane tunnel address information; wherein, the Xn interface is the interface name between gNB and gNB, and the F1 interface is the interface name between CU and DU under the CU-DU separation architecture.

[0170] The handover request response message also includes the configuration information of the target cell encapsulating the key parameters of the target cell.

[0171] If the target cell uses the same first configuration information as the source cell, the configuration information of the target cell does not include the first configuration information. If the target cell does not use the same first configuration information as the source cell, the configuration information of the target cell includes the first configuration information.

[0172] Exemplarily, the key parameter of the target cell may be a next hop chaining count (NCC) value.

[0173] Optionally, the handover request response message includes indication information 0, where the indication information 0 is used to indicate whether the target cell agrees to use the same first configuration information as that of the source cell.

[0174] If the target cell does not agree to use the same first configuration information as the source cell, and the S-gNB side does not provide UE1 with the configuration information of multiple candidate cells (including the target cell) in advance, then the configuration information of the target cell carried in the handover request response message also includes the first configuration information.

[0175] S403: The S-gNB sends a first handover command to UE1, where the first handover command is used to request UE1 to switch from the source cell to the target cell.

[0176] Correspondingly, the UE1 receives the first handover command sent by the S-gNB through the source cell. The first handover command includes the key parameter of the target cell.

[0177] After receiving the first handover command, UE1 does not re-establish PDCP if a connection with the target cell is not established, but retains the key of the source cell. In addition, after receiving the first handover command, when UE1 subsequently sends data, the bearer (or logical channel) corresponding to the data carries an identifier that can indicate the data type, or the transmitted data carries identification information that can indicate the data type.

[0178] Optionally, the first handover command carries configuration indication information, where the configuration indication information is used to indicate that the target cell uses the same first configuration information as the source cell. Corresponding to S402 above, if the target cell does not use the same first configuration information as the source cell, and the S-gNB does not pre-provide UE1 with configuration information of multiple candidate cells (including the target cell), then the first handover command may carry the configuration information of the target cell.

[0179] In the embodiment of the present application, after receiving the first handover command, UE1 may execute the following steps S404 and S405.

[0180] S404: UE1 sends a first response message to the S-gNB.

[0181] The first response message is used to notify the S-gNB that the UE1 accepts handover from the source cell to the target cell, or to notify the S-gNB that the UE1 has received the first handover command, which is not limited in this embodiment of the present application. The first response message can be: an RLC ACK message, a HARQ ACK message, an RRC message, a MAC CE, etc.

[0182] After receiving the first response message sent by UE1, the S-gNB suspends using the air interface communication link of the source cell to communicate with UE1.

[0183] S405: UE1 executes a processing flow based on the handover command.

[0184] In step S405, the processing flow executed by UE1 may specifically include but is not limited to one or more of the following steps:

[0185] (1) UE1 establishes a connection with the target cell;

[0186] (2) Configuration information of the effective target cell;

[0187] If the target cell uses the same configuration information as the source cell (i.e., the first configuration information), then in step (2), UE1 can maintain the first configuration information of the source cell. If the target cell does not use the same configuration information as the source cell (i.e., the first configuration information), then in step (2), UE1 can validate the configuration information of the target cell.

[0188] (3) Baseband adjustment for the target cell;

[0189] (4) Adjust the radio frequency unit for the target cell;

[0190] (5) Deducing the secret key of the target cell;

[0191] (6) Use the target cell’s secret key to encrypt and integrity protect the data.

[0192] In the above, the step of establishing a connection between UE1 and the target cell may include establishing a bearer / logical channel for transmitting data between UE1 and the target cell, and may also include establishing an air interface link, such as establishing a random access or random access-free target cell air interface connection.

[0193] When the target cell confirms to use the same first configuration information as the source cell, UE1 will maintain the hardware processing flow corresponding to the first configuration information, such as maintaining baseband processing, maintaining radio frequency unit processing, etc., which is conducive to UE1 quickly completing the connection establishment of the target cell.

[0194] Typically, steps (1) to (4) are performed first, and steps (5) and (6) are performed later, and steps (5) and (6) are equivalent to the process of UE1 re-establishing PDCP. The present embodiment does not specifically limit the order of executing steps (1) to (4).

[0195] After the steps related to establishing a connection between UE1 and the target cell are completed in S405 , the following S406A-S406B and / or S407A-S407B may be executed.

[0196] S406A: The S-gNB sends the first type of downlink data to the T-gNB.

[0197] The S-gNB may send downlink data of the first type (the first type of downlink data may be equivalent to the first downlink data in the solution described in FIG. 3 ) to the T-gNB based on the address information of the downlink user plane tunnel of the T-gNB obtained in S402 . The downlink data of the first type refers to a data packet encrypted and integrity-protected by the S-gNB using the key of the source cell. For example, it may be a PDCP protocol data unit (PDU) processed using the key of the source cell.

[0198] In this embodiment, if the first type of downlink data can be transmitted through the bearer (or channel logic) identified as 1, then in the above S405, in the step of establishing a connection between UE1 and the target cell, the bearer (or logical channel) corresponding to identifier 1 can be established.

[0199] In S406A, the S-gNB sends the first type of downlink data to the T-gNB through the bearer (or logical channel) corresponding to identifier 1. The T-gNB can identify (judge) that it is the first type of data based on identifier 1 corresponding to the bearer (or logical channel) receiving the first type of downlink data, and then choose to send it to UE1.

[0200] In other embodiments, the first type of downlink data sent by the S-gNB carries identification information 1, which is used to identify (or characterize) the first type of data.

[0201] Exemplarily, the S-gNB adds an identifier 1 to the header of a downlink data packet sent to the T-gNB, for example, by adding the identifier 1 to a PDCP packet header, an RLC packet header, or a MAC packet header. The identifier 1 is used to indicate the first type of data. Therefore, after receiving the downlink data packet, the T-gNB can read the identifier 1 from it, thereby determining that the downlink data packet is data of the first type, and then the T-gNB sends the downlink data to UE1.

[0202] S406B: T-gNB sends the first type of downlink data to UE1.

[0203] Correspondingly, UE1 receives the first type of downlink data from the S-gNB through the T-gNB; UE1 can identify (determine) that it is the first type of data by receiving the identifier 1 corresponding to the bearer (or logical channel) of the first type of downlink data, or by the identifier information 1 carried in the first type of downlink data, and then, UE1 will choose to use the key of the source cell to decrypt and perform integrity verification on the first type of downlink data.

[0204] S407A: UE1 sends the first type of uplink data to T-gNB.

[0205] Exemplarily, UE1 uses the air interface communication link of the target cell to send first type uplink data to the T-gNB (the first type uplink data may be equivalent to the first uplink data in the solution described in FIG. 3 ). The first type of uplink data refers to a data packet encrypted and integrity protected by UE1 using the key of the source cell. For example, a PDCP PDU.

[0206] Similar to the above S406A, in this embodiment, the first type of data can be transmitted through the bearer (or channel logic) identified as 1. In S407A, UE1 sends the first type of uplink data to the T-gNB through the bearer (or logical channel) corresponding to identifier 1. The T-gNB can identify (determine) that the data is the first type based on identifier 1 corresponding to the bearer (or logical channel) receiving the first type of uplink data, and then choose to send it to the S-gNB.

[0207] In some other embodiments, the first type of uplink data sent by UE1 carries identification information 1, and the identification information 1 is used to identify (or characterize) the first type of data.

[0208] For example, UE1 adds an identifier 1 to the header of an uplink data packet sent to the T-gNB, for example, by adding the identifier 1 to a PDCP packet header, an RLC packet header, or a MAC packet header. The identifier 1 is used to indicate the first type of data. Therefore, after receiving the uplink data packet, the T-gNB can read the identifier 1 from it and determine that the uplink data packet is the first type of data. The T-gNB then sends the uplink data to the S-gNB.

[0209] S407B: The T-gNB sends the first type of uplink data to the S-gNB.

[0210] The T-gNB may send the first type of uplink data to the S-gNB based on the address information of the S-gNB's uplink user plane tunnel obtained in S401. Furthermore, the S-gNB may decrypt and perform integrity verification on the first type of uplink data using the source cell's key. After completing the processing of the first type of uplink data, the S-gNB may further send the data to the UPF.

[0211] Optionally, UE1 can send the RLC status report to the S-gNB through steps S407A and S407B (equivalent to the first type of uplink data being the RLC status report), so that the S-gNB can know (perceive) which data has been successfully received by UE1 and which data has not been successfully received by UE1 in the following step S411B.

[0212] S406A-S406B are the S-gNB sending the first type of downlink data to UE1 via the T-gNB. S407A-S407B are the UE1 sending the first type of uplink data to the S-gNB via the T-gNB. In S405, after the connection between UE1 and the target cell is completed, S406A-S406B and / or S407A-S407B can be executed (equivalent to continuing communication between UE1 and the S-gNB) without waiting for all processing steps in S405 to complete, thereby reducing the duration of communication interruption caused by the execution of the processing steps for UE1. Furthermore, there is no restriction on the order in which S406A-S406B (i.e., the transmission of the first type of downlink data) and S407A-S407B (i.e., the transmission of the first type of downlink data) can be executed.

[0213] S408A: UE1 sends the second type of uplink data to T-gNB.

[0214] After S405 is completed (i.e., after UE1 executes the process), UE1 has successfully derived the target cell's key. UE1 can then use the target cell's key to encrypt and integrity-protect the uplink data to be transmitted, obtaining uplink data of the second type (which may be equivalent to the second uplink data in the solution described in FIG. 3 ), and send the second type of uplink data to the T-gNB.

[0215] Correspondingly, after the T-gNB receives the second type of uplink data, it can use the key of the target cell to decrypt and perform integrity verification on the second type of uplink data to obtain the uplink data (i.e., the original data).

[0216] In this embodiment, if the second type of uplink data is transmitted through the bearer (or channel logic) identified as 2, then in the above S405, the step of establishing a connection between UE1 and the target cell may include establishing a bearer (or logical channel) corresponding to identifier 2.

[0217] In S408A, UE1 sends uplink data of the second type to the T-gNB via the bearer (or logical channel) corresponding to identifier 2. The T-gNB can identify (determine) that the data is of the second type based on identifier 2 corresponding to the bearer (or logical channel) receiving the uplink data of the second type. Furthermore, in S408, the T-gNB decrypts and performs integrity verification on the uplink data of the second type, and then selects to send it to the UPF in the core network.

[0218] In some other embodiments, the second type of uplink data sent by UE1 carries identification information 2, and the identification information 2 is used to identify (or indicate) the second type of data.

[0219] For example, UE1 adds an identifier 2 to the header of the uplink data packet sent to the T-gNB, for example, in the PDCP header, RLC header, or MAC header. Identifier 2 is used to indicate the second type of data. Therefore, after receiving the uplink data packet from UE1, the T-gNB can read identifier 2 from it and determine that the uplink data packet is the second type of data. Then, in S408B described below, the T-gNB sends the uplink data to the UPF in the core network.

[0220] Optionally, UE1 can send an RRC reconfiguration completion message to T-gNB through step S408A (that is, the RRC reconfiguration completion message is equivalent to the second type of uplink data mentioned above), which is used to indicate that the configuration information of the target cell has been successfully applied, including that UE1 has validated the key of the target cell.

[0221] S408B: T-gNB sends uplink data to UPF.

[0222] The uplink data is the second type of uplink data from UE1 that has been decrypted and integrity checked.

[0223] In the above S408A-S408B, UE1 uses the key of the target cell to perform uplink transmission of the second type of data with T-gNB, and then T-gNB sends the data from UE1 to the UPF in the core network.

[0224] S409A: T-gNB sends path switching request information to AMF.

[0225] This path switch request message is used to request the core network device to switch the downlink data path from the path corresponding to the S-gNB to the path corresponding to the T-gNB. The path corresponding to the S-gNB (which may be equivalent to the first path in the solution described in FIG3 ) refers to the transmission path between the S-gNB and the UPF, and the path corresponding to the T-gNB (which may be equivalent to the second path in the solution described in FIG3 ) refers to the transmission path between the T-gNB and the UPF. For example, this path switch request message is used to request that the termination point address of the downlink user plane tunnel be switched from the S-gNB address to the T-gNB address.

[0226] In this embodiment of the present application, step S409A can be executed after step S408A. That is, after receiving the second type of uplink data sent by UE1, the T-gNB can know that UE1 has completed the processing flow in step S405. Then, UE1 can send a path switch request message to the AMF in the core network. Since both S408B and S409A are executed after S408A, the execution order of S408B and S409A is not specifically limited.

[0227] In one embodiment, step S409A can also be performed after S406A, that is, after the T-gNB receives the first type of downlink data sent by the S-gNB, the T-gNB sends a path switching request information to the AMF in the core network.

[0228] In another embodiment, step S409A can also be performed after S407A, that is, after the T-gNB receives the first type of uplink data sent by UE1, the T-gNB sends a path switching request information to the AMF in the core network.

[0229] S409B: Path switching is performed between AMF and UPF.

[0230] The path switching process (procedure) for executing UE1 between AMF and UPF can be specifically implemented with reference to the existing technology and will not be described in detail here. It should be understood that the path switching process executed between AMF and UPF may also involve the participation of SMF.

[0231] After S409B, the core network equipment completes the switching of the downlink data path, that is, switching from the path corresponding to the S-gNB to the path corresponding to the T-gNB (that is, switching from the transmission path between the S-gNB and UPF to the transmission path between the T-gNB and UPF).

[0232] S409C: The AMF sends a path switch response message to the T-gNB.

[0233] Correspondingly, the T-gNB receives the path switching response information, which is used to indicate that the above-mentioned path switching has been completed.

[0234] S410A: The UPF sends downlink data to the T-gNB.

[0235] In step S410A, after the T-gNB receives the downlink data (unencrypted original data) from the UPF, it can use the key of the target cell to encrypt and integrity protect the downlink data to obtain the second type of downlink data.

[0236] S410B: T-gNB sends the second type of downlink data to UE1.

[0237] Accordingly, UE1 can receive the second type of downlink data sent by the T-gNB through the target cell (the second type of downlink data may be equivalent to the second downlink data in the solution described in FIG. 3 ). UE1 can identify (determine) that it is the second type of data by receiving the identifier 2 corresponding to the bearer (or logical channel) of the second type of downlink data, or by the identifier information 2 carried in the second type of downlink data. UE1 then chooses to use the target cell's key to decrypt and perform integrity verification on the second type of downlink data.

[0238] Since UE1 has already derived the secret key of the target cell and completed the path switching, in step S410B, UE1 can also use the secret key of the target cell to decrypt and perform integrity verification on the second type of downlink data to obtain the original data.

[0239] S411A: T-gNB sends indication information 1 to S-gNB.

[0240] Correspondingly, the S-gNB receives the indication information 1 from the T-gNB.

[0241] The indication information 1 is used to instruct the S-gNB to stop generating the first type of downlink data and stop sending the first type of downlink data.

[0242] In this embodiment, since the first type of uplink data / downlink data is transmitted using the bearer (or logical channel) corresponding to identifier 1, the S-gNB will also release the bearer (or logical channel) corresponding to identifier 1 according to indication information 1.

[0243] S411B: The S-gNB sends data transmission status information and data forwarding information to the T-gNB.

[0244] The data transmission status information is used to inform the sequence numbers (or IDs) of successfully sent and / or unsuccessfully sent data packets, for example, a sequence number status transmission message is sent to indicate the reception status of the uplink data sequence number and the transmission status of the downlink data sequence number.

[0245] Optionally, the S-gNB sends unsuccessfully transmitted downlink data packets (i.e., original data packets without encryption and integrity protection), such as PDCP service data units (SDUs), to the target gNB. This allows the target gNB to continue sending unsuccessfully transmitted data packets from the S-gNB to UE1. For uplink data packets, the S-gNB may deliver sequenced data packets to the UPF (e.g., data packets with sequence numbers 1, 2, and 3, which increase in sequence by 1), while sending unsequenced data packets to the T-gNB (e.g., data packets with sequence numbers 6, 7, and 9, which have sequence number holes). The T-gNB then delivers them to the UPF after sequence completion (i.e., after the sequence number holes are filled).

[0246] S412A: T-gNB sends indication information 2 to UE1.

[0247] Correspondingly, UE1 receives the indication information 2 from T-gNB.

[0248] The indication information 2 may be used to instruct the UE1 to stop using the source cell key for data processing and to stop processing operations related to the source cell key, and may also instruct the UE1 to delete the source cell key.

[0249] In this embodiment, the first type of uplink data / downlink data is transmitted using the bearer (or logical channel) corresponding to the identifier 1. Therefore, the UE 1 may also release the bearer (or logical channel) corresponding to the identifier 1 according to the indication information 2.

[0250] In addition, after receiving the indication information 2, UE1 no longer carries the relevant identifier of the first type of data in the data packet (the relevant identifier of the first type of data is equivalent to the first target identifier in the scheme described in Figure 3 above), such as the above-mentioned identifier 1 of bearer 1, identifier 1 of logical channel 1, and identifier 1, and no longer carries the relevant identifier of the second type of data in the data packet (the relevant identifier of the second type of data is equivalent to the second target identifier in the scheme described in Figure 3 above), such as the above-mentioned identifier 2 of bearer 2, identifier 2 of logical channel 2, and identifier 2.

[0251] In the embodiment of the present application, the above-mentioned S411A and S412A can be executed synchronously or asynchronously, and the order of execution is not specifically limited.

[0252] S412B: UE1 sends feedback information to T-gNB.

[0253] This feedback information is used to inform T-gNB that UE1 has successfully received indication information 2.

[0254] After S411B and / or S412B (i.e., when receiving status information and data fed back by the S-gNB, or when receiving feedback information from UE1, or when receiving status information and data of data transmission fed back by the S-gNB and feedback information from UE1), the T-gNB may no longer carry relevant identifiers of the first type of data (for example, the identifier 1 of bearer 1, the identifier of logical channel 1, and identifier 1 mentioned above) with the data packet, and no longer carry relevant identifiers of the second type of data (for example, the identifier 2 of bearer 2, the identifier 2 of logical channel 2, and identifier 2 mentioned above) with the data packet.

[0255] In this embodiment one, taking UE1 as an example, for the scenario where UE1 switches base stations (or UE switches cells), during the switching processing of UE1 (including the UE1 execution processing flow and the path switching flow between the target base station and the core network), UE1 can maintain data transmission with the source base station through the air interface link of the target base station, thereby effectively reducing the duration of communication interruption due to the execution of switching by UE1.

[0256] Example 2:

[0257] Based on the CU-DU split architecture shown in Figure 2, a base station can be logically divided into a centralized unit (CU) and one or more distributed units (DUs). Each DU connects to the CU via the F1 logical interface. Operations related to the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers are handled by the DU, while operations related to the Service Data Adaptation Protocol (SDAP), Radio Resource Control (RRC), and Packet Data Convergence Protocol (PDCP) layers are handled by the CU.

[0258] In this second embodiment, specifically, the source base station (S-gNB) is divided into an S-gNB-CU (hereinafter referred to as the source CU) and an S-gNB-DU (hereinafter referred to as the source DU), and the target base station (T-gNB) is divided into a T-gNB-CU (hereinafter referred to as the target CU) and a T-gNB-DU (hereinafter referred to as the target DU). The specific implementation of steps (S501 to S512B) described in this second embodiment can refer to the specific implementation of steps (S401 to S412B) described in the first embodiment above, and will not be described in detail here. The steps shown in this second embodiment can be a detailed description of the information exchange in the solution described in the first embodiment. Referring to Figure 5, the process of this second embodiment is as follows:

[0259] Specifically, the specific path of the downlink transmission in this embodiment can be seen in Figure 6A, and the specific path of the uplink transmission in this embodiment can be seen in Figure 6B, where the path corresponding to line 1 represents the transmission path before UE1 switches, line 2 represents the transmission path during UE1 switching, and line 3 represents the transmission path after UE1 switches.

[0260] S501: The source CU (S-gNB-CU) sends a handover request message to the target CU (T-gNB-CU).

[0261] It should be understood that after receiving the handover request message, the target CU sends the relevant information in the handover request message to the target DU through the F1 interface, for example, sending the first configuration information of the source cell to the target DU and requesting the target DU to use the same configuration information as the first configuration information. The interaction process between the target CU and the target DU is omitted in the figure.

[0262] S502: The target CU (T-gNB-CU) sends a handover request response message to the source CU (S-gNB-CU).

[0263] S503: The source DU (S-gNB-DU) sends a first handover command to UE1, where the first handover command is used to request UE1 to switch from the source cell to the target cell.

[0264] The first handover command may be an RRC message, which is sent by the source CU to the source DU, which is then sent by the source DU to UE1. The first handover command may also be a MAC CE or downlink control information (DCI) message, which is generated by the source DU itself and sent to UE1. The interaction process between the source CU and the source DU is omitted in the figure.

[0265] S504: UE1 sends a first response message to the source DU (S-gNB-DU).

[0266] Optionally, the source DU further sends a first response message to the source CU. The interaction process between the source CU and the source DU is omitted in the figure.

[0267] S505: UE1 executes a processing flow based on the handover command.

[0268] S506A: The source CU (S-gNB-CU) sends the first type of downlink data to the target DU (T-gNB-DU).

[0269] It should be understood that in a possible network deployment, there is no direct communication connection between the source CU and the target DU, then the first type of downlink data may also be transferred and sent through the target CU, that is, the source CU sends it to the target CU, and the target CU further sends it to the target DU.

[0270] S506B: The target DU (T-gNB-DU) sends the first type of downlink data to UE1.

[0271] The specific transmission path corresponding to the above steps S506A-S506B can refer to the path shown by line 2 in FIG6A to transmit the first type of downlink data.

[0272] S507A: UE1 sends the first type of uplink data to the target DU (T-gNB-DU).

[0273] S507B: The target DU (T-gNB-DU) sends the first type of uplink data to the source CU (S-gNB-CU).

[0274] It should be understood that in a possible network deployment, there is no direct communication connection between the source CU and the target DU, then the first type of uplink data may also be sent via the target CU, that is, the target DU is sent to the target CU, and the target CU is further sent to the source U.

[0275] The specific transmission path corresponding to the above steps S507A-S507B can refer to the path shown by line 2 in FIG6B to transmit the first type of uplink data.

[0276] S508A: UE1 sends the second type of uplink data to the target DU (T-gNB-DU).

[0277] Furthermore, the target DU sends the uplink data to the target CU via the F1 interface, which is not shown in FIG5 .

[0278] S508B: The target CU (T-gNB-CU) sends uplink data to the UPF.

[0279] In the above step S508A, the specific transmission path for UE1 to send the second type of uplink data to T-gNB can refer to the path shown by line 3 in Figure 6B.

[0280] S509A: The target CU (T-gNB-CU) sends a path switch request message to the AMF.

[0281] S509B: Path switching is performed between AMF and UPF.

[0282] S509C: AMF sends path switch response information to the target CU (T-gNB-CU).

[0283] S510A: The UPF sends downlink data to the target CU (T-gNB-CU).

[0284] Furthermore, the target CU sends the downlink data to the target DU via the F1 interface, which is not shown in FIG5 .

[0285] S510B: The target DU (T-gNB-DU) sends the second type of downlink data to UE1.

[0286] In step S510B, the specific transmission path for T-gNB to send the second type of downlink data to UE1 can refer to the path shown by line 3 in Figure 6A.

[0287] S511A: The target CU (T-gNB-CU) sends indication information 1 to the source CU (S-gNB-CU).

[0288] S511B: The source CU (S-gNB-CU) sends data transmission status information and data forwarding to the target CU (T-gNB-CU).

[0289] S512A: The target DU (T-gNB-DU) sends indication information 2 to UE1.

[0290] The indication information 2 may be an RRC message, which is sent by the target CU to the target DU, which is then sent by the target DU to UE1. The first handover command may also be a MAC CE or DCI message, which is generated by the target DU itself and sent to UE1. The interaction process between the target CU and the target DU is omitted in the figure.

[0291] S512B: UE1 sends feedback information to the target DU (T-gNB-DU).

[0292] Example 3:

[0293] The difference between this third embodiment and the first embodiment is that after UE1 accesses the target cell through the target cell's air interface link, the target base station can obtain the target cell's key parameters from the AMF in the core network and send the target cell's key parameters to UE1. Referring to Figure 7, the process of this third embodiment is as follows:

[0294] The specific implementation of steps S701 to S704 may refer to the specific implementation of steps S401 to S404 in the first embodiment, and will not be described in detail here.

[0295] However, unlike step S401 above, the handover request message in step S701 does not include the target cell's key or key parameters derived by the source cell. Unlike step S402 above, the handover request response message in step S702 does not include the target cell's key parameters. Unlike step S403 above, the first handover command in step S703 does not include the target cell's key parameters.

[0296] S705: UE1 establishes a connection with the target cell.

[0297] In step S705, one or more of the following steps may be performed:

[0298] (1) UE1 establishes a connection with the target cell;

[0299] (2) Configuration information of the effective target cell;

[0300] If the target cell uses the same configuration information as the source cell (such as the first configuration information), then in this step, UE1 can maintain the configuration information of the source cell. If the target cell does not agree to use the same configuration information as the source cell, then in this step, UE1 can implement the configuration information of the target cell.

[0301] (3) Baseband adjustment for the target cell;

[0302] (4) Adjust the radio frequency unit for the target cell.

[0303] Through this step, UE1 successfully accesses the target cell and can then execute the following steps S706A-S706B and / or S707A-S707B.

[0304] S706A: The S-gNB sends the first type of downlink data to the T-gNB.

[0305] S706B: T-gNB sends the first type of downlink data to UE1.

[0306] The specific implementation of the above steps S706A-S706B can refer to the specific implementation of the above steps S406A-S406B one by one, and will not be described in detail here.

[0307] S707A: UE1 sends the first type of uplink data to T-gNB.

[0308] S707B: T-gNB sends the first type of uplink data to S-gNB.

[0309] The specific implementation of the above steps S707A-S707B can refer to the specific implementation of the above steps S407A-S407B one by one, and will not be described in detail here.

[0310] In S707A, when the T-gNB receives the first type of uplink data, it can execute the following S708A.

[0311] Optionally, the T-gNB may also execute the following S708A after the above S706A, that is, after receiving the first type of downlink data sent by the S-gNB, the T-gNB sends a path switching request information to the AMF.

[0312] S708A: T-gNB sends path switching request information to AMF.

[0313] S708B: Path switching is performed between AMF and UPF.

[0314] S708C: AMF sends path switching response information to T-gNB.

[0315] The specific implementation of the above steps S708A-S708C can refer to the specific implementation of the above steps S409A-S409C one by one, and will not be described in detail here.

[0316] However, it is different from the above S409C. The path switching request response information in step S708C carries the key parameters of the target cell, specifically, it can include key parameter 1 and key parameter 2; wherein, key parameter 1 is sent to UE1, and UE1 deduces the key of the target cell; key parameter 2 is used by the network device to which the target cell belongs to deduce the key of the target cell.

[0317] During the process of performing path switching between the AMF and the UPF (which may include the above steps S708A-S708C), UE1 can refer to the above steps S706A-S706B and / or S707A-S707B, and use the key of the source cell to transmit the first type of data through the T-gNB and the S-gNB, which will not be described in detail here.

[0318] S709: T-gNB sends the key parameters of the target cell to UE1.

[0319] After receiving the key parameter of the target cell (eg, key parameter 1 in S708C), UE1 may perform the following key derivation process of the target cell in S710 .

[0320] S710: UE1 executes a processing flow based on the handover command.

[0321] Specifically, in step S710, UE1 performs the derivation of the target cell's key and uses the target cell's key to encrypt and integrity protect the data. This can be achieved by referring to (5) and (6) in S405 above. Steps (5) and (6) are equivalent to the process of UE1 re-establishing PDCP. However, unlike S405 above, step S710 does not include the steps related to UE1 establishing a connection with the target cell (such as steps (1) to (4) described in S405). The steps related to UE1 establishing a connection with the target cell are completed in S705 above.

[0322] After S710, UE1 can deduce the key of the target cell, and then use the key of the target cell to perform the second type of data transmission with T-gNB.

[0323] S711A: UE1 sends the second type of uplink data to T-gNB.

[0324] S711B: T-gNB sends uplink data to UPF.

[0325] The specific implementation of the above steps S711A-S711B can refer to the specific implementation of the above steps S408A-S408B one by one, and will not be described in detail here.

[0326] S712A: UPF sends downlink data to T-gNB.

[0327] S712B: T-gNB sends the second type of downlink data to UE1.

[0328] The specific implementation of the above steps S712A-S712B can refer to the specific implementation of the above steps S410A-S410B one by one, and will not be described in detail here.

[0329] S713A: T-gNB sends indication information 1 to S-gNB.

[0330] S713B: The S-gNB sends data transmission status information and data forwarding to the T-gNB.

[0331] The specific implementation of the above steps S713A-S713B can refer to the specific implementation of the above steps S411A-S411B one by one, and will not be described in detail here.

[0332] S714A: T-gNB sends indication information 2 to UE1.

[0333] S714B: UE1 sends feedback information to T-gNB.

[0334] The specific implementation of the above steps S714A-S714B can refer to the specific implementation of the above steps S412A-S412B, which will not be described in detail here.

[0335] In the solution described in the first embodiment above, the target cell key parameters obtained by the target base station are provided by the source base station, and the source base station carries the target cell key parameters in the first handover command and sends it to UE1. Therefore, the source base station can obtain the target cell key parameters and thus the target cell key. In this third embodiment, the target base station can directly obtain the new target cell key parameters from the AMF, thereby effectively avoiding security risks.

[0336] It should be noted that the solution described in the third embodiment can also be applied to the CU-DU separation architecture shown in Figure 2. The specific interaction method can be implemented with reference to the interaction method described in the above second embodiment and will not be described in detail here.

[0337] In the embodiments provided in the present application, the methods provided in the embodiments of the present application are introduced from the perspective of interaction between various devices. In order to implement the various functions in the methods provided in the embodiments of the present application, the terminal device or the first access network device or the second access network device may include a hardware structure and / or a software module to implement the above functions in the form of a hardware structure, a software module, or a hardware structure plus a software module. Whether one of the above functions is executed in the form of a hardware structure, a software module, or a hardware structure plus a software module depends on the specific application and design constraints of the technical solution.

[0338] The division of modules in the embodiments of the present application is illustrative and is merely a logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in the various embodiments of the present application may be integrated into a single processor, or may exist physically separately, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or software functional modules.

[0339] Similar to the above concept, as shown in FIG8 , an embodiment of the present application further provides a communication device 800 for implementing the functions of the terminal device, the first access network device, or the second access network device in the above method. For example, the communication device 800 may be a software module or a chip system. In the embodiment of the present application, the chip system may be composed of a chip, or may include a chip and other discrete components. The communication device 800 may include: a communication unit 801 and a processing unit 802.

[0340] In the embodiments of the present application, the communication unit 801 may also be referred to as a transceiver unit, and may include a transmitting unit and / or a receiving unit, respectively configured to execute the steps of transmitting and receiving by the terminal device, the first access network device, or the second access network device in the above method embodiments. The processing unit 802 may be configured to read instructions and / or data from the storage module to enable the communication device 800 to implement the above method embodiments.

[0341] Optionally, the communication device 800 may further include a storage unit 803 , which is equivalent to a storage module and may be used to store instructions and / or data.

[0342] The communication device provided in the embodiments of the present application is described in detail below in conjunction with Figures 8 and 9. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for matters not described in detail, reference can be made to the method embodiments described in Figures 3, 4, 5, and 7 above. For the sake of brevity, they will not be repeated here.

[0343] The communication unit 801 may also be referred to as a transceiver, transceiver, or transceiver device. The processing unit may also be referred to as a processor, processing board, processing module, or processing device. Alternatively, the device in the communication unit 801 that implements the receiving function may be considered a receiving unit, and the device in the communication unit 801 that implements the transmitting function may be considered a transmitting unit. That is, the communication unit 801 includes both a receiving unit and a transmitting unit. A communication unit may also be referred to as a transceiver, transceiver, or transceiver circuit. A receiving unit may also be referred to as a receiver, receiver, or receiving circuit. A transmitting unit may also be referred to as a transmitter, transmitter, or transmitting circuit.

[0344] When the communication device 800 executes the terminal device in the process shown in FIG. 3 in the above embodiment:

[0345] The communication unit 801 is configured to receive a first handover message from a first access network device, where the first handover message is used to instruct the terminal device to handover from a currently located first cell to a second cell, where the second cell is a cell under the jurisdiction of the second access network device;

[0346] The processing unit 802 is configured to perform first data transmission with the second access network device using the key of the first cell based on the first handover message.

[0347] When the communication apparatus 800 executes the first access network device in the process shown in FIG. 3 in the above embodiment:

[0348] The communication unit 801 is configured to send a first handover message to a terminal device, where the first handover message is used to instruct the terminal device to switch from a first cell to a second cell, where the second cell is a cell under the jurisdiction of a second access network device;

[0349] The communication unit 801 is further configured to perform first data transmission with the second access network device using the secret key of the first cell.

[0350] The processing unit 802 is used to process data and / or information.

[0351] When the communication apparatus 800 executes the second access network device in the process shown in FIG. 3 in the above embodiment:

[0352] The communication unit 801 is used to receive downlink first data from the first access network device and send the downlink first data to the terminal device; and / or receive uplink first data from the terminal device and send the uplink first data to the first access network device; wherein the first data is data obtained by encryption and integrity protection using the key of the first cell.

[0353] The processing unit 802 is used to process data and / or information.

[0354] The above is just an example. The processing unit 802 and the communication unit 801 can also perform other functions. For more detailed description, please refer to the relevant description in the method embodiment shown in Figure 3, which is not repeated here.

[0355] FIG9 shows a communication device 900 provided in an embodiment of the present application. The communication device shown in FIG9 may be a hardware circuit implementation of the communication device shown in FIG8 . The communication device 900 can be applied to the flowchart shown above to perform the functions of the terminal device, the first access network device, or the second access network device in the above-described method embodiment. For ease of illustration, FIG9 only shows the main components of the communication device.

[0356] As shown in Figure 9, communication device 900 includes a communication interface 901 and a processor 902. Communication interface 901 and processor 902 are coupled to each other. It is understood that communication interface 901 can be a transceiver or an input / output interface, or an interface circuit such as a transceiver circuit. Optionally, communication device 900 can also include a memory 903 for storing instructions executed by processor 902, input data required by processor 902 to execute instructions, or data generated by processor 902 after executing instructions.

[0357] When the communication device 900 is used to implement the methods shown in FIG. 3 , FIG. 4 , FIG. 5 and FIG. 7 , the communication interface 901 is used to implement the functions of the above-mentioned communication unit 801 , and the processor 902 is used to implement the functions of the above-mentioned processing unit 802 .

[0358] The specific connection medium between the communication interface 901, processor 902, and memory 903 is not limited in the embodiments of the present application. In Figure 9, the embodiment of the present application shows that the memory 903, processor 902, and communication interface 901 are connected via a communication bus 904. The communication bus 904 is represented by a bold line in Figure 9. The connection methods between other components are only for schematic illustration and are not limiting. The communication bus 904 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one bold line is used in Figure 9, but this does not mean that there is only one bus or one type of bus.

[0359] When the communication device is a chip, FIG10 shows a simplified schematic diagram of the chip structure, wherein the chip 1000 includes an interface circuit 1001 and one or more processors 1002. Optionally, the chip 1000 may further include a bus.

[0360] The processor 1002 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above-mentioned communication method can be completed by an integrated logic circuit of hardware in the processor 1002 or instructions in the form of software. The above-mentioned processor 1002 can be a general-purpose processor, a digital communicator (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The various methods and steps disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0361] The interface circuit 1001 can be used to send or receive data, instructions or information. The processor 1002 can use the data, instructions or other information received by the interface circuit 1001 to process it, and can send the processing completion information through the interface circuit 1001.

[0362] Optionally, the chip further includes a memory 1003, which may include a read-only memory and a random access memory, and provides operating instructions and data to the processor. A portion of the memory 1003 may also include a non-volatile random access memory (NVRAM).

[0363] Optionally, the memory stores an executable software module or a data structure, and the processor can perform corresponding operations by calling an operation instruction stored in the memory (the operation instruction may be stored in an operating system).

[0364] Optionally, the chip can be used in a terminal device, a first access network device, or a second access network device involved in an embodiment of the present application. Optionally, the interface circuit 1001 can be used to output the execution result of the processor 1002. For the communication method provided in one or more embodiments of the present application, reference can be made to the aforementioned embodiments and will not be repeated here.

[0365] It should be noted that the corresponding functions of the interface circuit 1001 and the processor 1002 can be implemented through hardware design, software design, or a combination of hardware and software, and there is no limitation here.

[0366] An embodiment of the present application also provides a computer-readable storage medium on which computer instructions are stored for implementing the method executed by the terminal device or the first access network device or the second access network device in the above method embodiment.

[0367] For example, when the computer program is executed by a computer, the computer can implement the method performed by the terminal device or the first access network device or the second access network device in the above method embodiment.

[0368] An embodiment of the present application also provides a computer program product comprising instructions, which, when executed by a computer, enables the computer to implement the method executed by the terminal device or the first access network device or the second access network device in the above method embodiment.

[0369] An embodiment of the present application also provides a chip, including a processor, for calling the computer program or computer instructions stored in the memory so that the processor executes the communication method of the embodiments shown in Figures 3, 4, 5 and 7 above.

[0370] In one possible implementation, the input of the chip corresponds to the receiving operation in the embodiments shown in Figures 3, 4, 5 and 7 above, and the output of the chip corresponds to the sending operation in the embodiments shown in Figures 3, 4, 5 and 7 above.

[0371] Optionally, the processor is coupled to the memory via an interface.

[0372] Optionally, the chip further includes a memory in which computer programs or computer instructions are stored.

[0373] The processor mentioned in any of the above may be a general-purpose central processing unit, a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of a program of a communication method according to the embodiments shown in FIG3 , FIG4 , FIG5 , and FIG7 . The memory mentioned in any of the above may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, a random access memory (RAM), etc.

[0374] It should be noted that, for the sake of convenience and brevity of description, the explanation and beneficial effects of the relevant contents in any of the communication devices provided above may refer to the corresponding communication method embodiments provided above, and will not be repeated here.

[0375] In the present application, the communication devices may further include a hardware layer, an operating system layer running on top of the hardware layer, and an application layer running on the operating system layer. The hardware layer may include hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also known as main memory). The operating system of the operating system layer may be any one or more computer operating systems that implement business processing through processes, such as the Linux operating system, Unix operating system, Android operating system, iOS operating system, or Windows operating system. The application layer may include applications such as browsers, address books, word processing software, and instant messaging software.

[0376] The division of modules in the embodiments of the present application is illustrative and is merely a logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in the various embodiments of the present application may be integrated into a single processor, or may exist physically separately, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or software functional modules.

[0377] Through the description of the above embodiments, it will be clear to those skilled in the art that the embodiments of the present application can be implemented in hardware, firmware, or a combination thereof. When software is used for implementation, the above functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any medium that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that a computer can access. For example, but not limited to: a computer-readable medium may include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition, any connection can be appropriately a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. As used in the embodiments of the present application, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically and discs use lasers to reproduce data optically. Combinations of the above should also be included within the scope of protection of computer-readable media.

[0378] In short, the above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent replacements, improvements, etc. made based on the disclosure of the present application should be included in the scope of protection of the present application.

Claims

1. A communication method, characterized in that: The method is applied to a terminal device, comprising: Receiving a first handover message from a first access network device, where the first handover message is used to instruct the terminal device to switch from a first cell currently located to a second cell, where the second cell is a cell under the jurisdiction of the second access network device; Based on the first switching message, a secret key of the first cell is used to perform first data transmission with the second access network device.

2. The method according to claim 1, characterized in that The first handover message includes cell configuration indication information, where the cell configuration indication information is used to indicate that the second cell uses the same configuration information as the first cell.

3. The method according to claim 1 or 2, characterized in that: The using the secret key of the first cell to perform first data transmission with the second access network device includes: When a communication connection is established with the second cell and the secret key of the second cell is not derived, the secret key of the first cell is used to perform first data transmission with the second access network device.

4. The method according to claim 3, characterized in that The using the secret key of the first cell to perform first data transmission with the second access network device includes: Using the secret key of the first cell to encrypt and integrity protect the uplink data to obtain uplink first data; sending the uplink first data to the second access network device; and / or Receive downlink first data from the second access network device, and use the secret key of the first cell to decrypt and perform integrity verification on the downlink first data.

5. The method according to claim 3, characterized in that: After establishing a communication connection with the second cell, the method further includes: receiving configuration information of a key of the second cell from the second access network device.

6. The method according to any one of claims 3 to 5, characterized in that The method further comprises: The first data is identified by a first target identifier, where the first target identifier is any one of the following: An identifier of a first bearer, an identifier of a first logical channel, and a first identifier carried in the first data; wherein the first bearer or the first logical channel is used to transmit the first data.

7. The method according to any one of claims 1 to 6, characterized in that After deducing the secret key of the second cell, the method further includes: Using the secret key of the second cell to perform encryption and integrity protection processing on the uplink data to obtain uplink second data; sending the uplink second data to the second access network device; and / or Receive downlink second data from the second access network device, and use the secret key of the second cell to decrypt and perform integrity verification on the downlink second data.

8. The method according to claim 7, characterized in that The method further comprises: The second data is identified by a second target identifier, where the second target identifier is any one of the following: An identifier of a second bearer, an identifier of a second logical channel, and a second identifier carried in the second data; wherein the second bearer or the second logical channel is used to transmit the second data.

9. The method according to any one of claims 1 to 8, characterized in that The method further comprises: Receive first indication information from the second access network device, where the first indication information is used to instruct the terminal device to perform one or more of the following: Stop using the key of the first cell to process data, delete the key of the first cell, stop processing associated with the key of the first cell, release the first bearer or first logical channel of the first data, and stop carrying the second identifier in the second data.

10. A communication method, characterized in that: The communication method is applied to a first access network device, comprising: Sending a first switching message to a terminal device, where the first switching message is used to instruct the terminal device to switch from a first cell currently located to a second cell, where the second cell is a cell under the jurisdiction of a second access network device; Use the secret key of the first cell to perform first data transmission with the second access network device.

11. The method according to claim 10, characterized in that Before sending the first switching message to the terminal device, the method further includes: sending first switching request information to the second access network device, wherein the first switching request information includes address information of a user plane tunnel of the first access network device; A first switching response message is received from the second access network device, where the first switching response message includes address information of a user plane tunnel of the second access network device.

12. The method according to claim 11, characterized in that The first switching request information also includes third indication information, and the third indication information is used to request the second cell to use the configuration information of the first cell; the first switching response information is used to indicate that the second cell confirms the use of the configuration information of the first cell; wherein the configuration information of the first cell includes the uplink physical layer channel configuration information of the first cell and the downlink physical layer channel configuration information of the first cell.

13. The method according to any one of claims 10 to 12, characterized in that Before using the secret key of the first cell to transmit the first data with the second access network device, the method further includes: receiving a first response message from the terminal device, where the first response message is used to notify the terminal device to confirm switching from the first cell to the second cell; The using the secret key of the first cell to perform first data transmission with the second access network device includes: Using the secret key of the first cell to encrypt and integrity protect the downlink data, to obtain downlink first data; sending the downlink first data to the second access network device according to the address information of the user plane tunnel of the second access network device; and / or Receive uplink first data from the second access network device, use the secret key of the first cell to decrypt and perform integrity verification on the uplink first data, and obtain uplink data.

14. The method according to any one of claims 10 to 13, characterized in that The method further comprises: receiving second indication information from the second access network device, where the second indication information is used to instruct the first cell or the first access network device to stop generating or sending the first data, and to release a first bearer or a first logical channel of the first data; Sending first status information to the second access network device, where the first status information is used to indicate identification information of the first data that has been successfully sent and / or unsuccessfully sent.

15. The method according to claim 14, characterized in that The method further comprises: Sending third data to the second access network device, where the third data is the unsuccessfully sent data that has not been encrypted and integrity protected.

16. The method according to any one of claims 10 to 15, characterized in that The method further comprises: The first data is identified by a first target identifier, where the first target identifier is any one of the following: An identifier of a first bearer, an identifier of a first logical channel, and a first identifier carried in the first data; wherein the first bearer or the first logical channel is used to transmit the first data.

17. A communication method, characterized in that: The communication method is applied to a second access network device, comprising: Receive first downlink data from the first access network device, and send the first downlink data to the terminal device; and / or receiving first uplink data from the terminal device, and sending the first uplink data to the first access network device; The first data is data obtained by performing encryption and integrity protection processing using the secret key of the first cell.

18. The method according to claim 17, characterized in that The method further comprises: receiving first switching request information from the first access network device, where the first switching request information includes address information of a user plane tunnel of the first access network device; Sending first switching response information to the first access network device, where the first switching response information includes address information of the user plane tunnel of the second access network device.

19. The method according to claim 18, characterized in that The first switching request information also includes third indication information, and the third indication information is used to request the second cell to use the configuration information of the first cell; the first switching response information is used to indicate that the second cell confirms the use of the configuration information of the first cell; wherein the configuration information of the first cell includes the uplink physical layer channel configuration information of the first cell and the downlink physical layer channel configuration information of the first cell.

20. The method according to claim 18, characterized in that The sending the uplink first data to the first access network device includes: The uplink first data is sent to the first access network device according to the address information of the user plane tunnel of the first access network device.

21. The method according to any one of claims 17 to 20, characterized in that The method further comprises: receiving uplink second data from the terminal device; decrypting and integrity checking the uplink second data using the secret key of the second cell to obtain uplink data; sending the uplink data to a user plane function network element in a core network device; and / or Receive downlink data from the user plane functional network element in the core network device and / or the first access network device; use the secret key of the second cell to encrypt and integrity protect the downlink data to obtain downlink second data; and send the downlink second data to the terminal device.

22. The method according to claim 17 or 21, characterized in that The method further comprises: After the first event, a path switching request message is sent to an access and mobility management function network element in a core network device; the path switching request message is used to request that a data transmission path be switched from a first path corresponding to a user plane function network element and the first access network device to a second path corresponding to a user plane function network element and the second access network device; the first event is any one of the following: The first downlink data is received from the first access network device, the first uplink data is received from the terminal device, and the second uplink data is received from the terminal device.

23. The method according to claim 22, characterized in that The method further comprises: receiving a path switch response message from the access and mobility management function network element, and acquiring configuration information of a secret key of the second cell from the path switch response message; The path switching response information is used to indicate that the data transmission path has been switched from the first path to the second path.

24. The method according to claim 23, characterized in that The method further comprises: Sending first indication information to the terminal device, and sending second indication information to the first access network device; The first indication information is used to instruct the terminal device to perform one or more of the following: Stop using the key of the first cell to process data, delete the key of the first cell, stop processing associated with the key of the first cell, release the first bearer or first logical channel of the first data, and stop carrying the second identifier in the second data; The second indication information is used to instruct the first cell or the first access network device to stop generating or sending the first data and release the first bearer or first logical channel of the first data.

25. The method according to claim 23, characterized in that The method further comprises: First status information is received from the first access network device, where the first status information is used to indicate identification information of the first data that has been successfully sent and / or unsuccessfully sent.

26. The method according to claim 25, characterized in that The method further comprises: The third data is received from the first access network device, where the third data is the unsuccessfully sent data that is not encrypted and integrity protected.

27. The method according to any one of claims 17 to 26, characterized in that The method further comprises: The first data is identified by a first target identifier, where the first target identifier is any one of the following: an identifier of a first bearer, an identifier of a first logical channel, and a first identifier carried in the first data; the first bearer or the first logical channel is used to transmit the first data; The second data is identified by a second target identifier, where the second target identifier is any one of the following: An identifier of a second bearer, an identifier of a second logical channel, and a first identifier carried in the second data; the second bearer or the second logical channel is used to transmit the second data.

28. A communication device, characterized in that: The method comprises a module or a unit for executing the method according to any one of claims 1 to 9, or a module or a unit for executing the method according to any one of claims 10 to 16, or a module or a unit for executing the method according to any one of claims 17 to 27.

29. A communication device, characterized in that: The invention comprises a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method as described in any one of claims 1 to 9, or implement the method as described in any one of claims 10 to 16, or implement the method as described in any one of claims 17 to 27 through a logic circuit or executing code instructions.

30. A communication system, characterized in that: include: A terminal device and a first access network device and a second access network device; the terminal device is used to implement the method described in any one of claims 1 to 9, the first access network device is used to implement the method described in any one of claims 10 to 16, and the second access network device is used to implement the method described in any one of claims 17 to 27.

31. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a communication device, implements the method according to any one of claims 1 to 27.

32. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or an instruction, and when the computer program or the instruction is executed by the communication device, the method according to any one of claims 1 to 27 is implemented.

33. A chip system, characterized in that: include: A processor configured to execute the method according to any one of claims 1 to 27.

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