Communication method, terminal, network device, system, and storage medium

Abstract

The present disclosure provides a communication method, a terminal, a network device, a system, and a storage medium. The method comprises: receiving a first media access control element (MAC CE) sent by a network device; and determining, on the basis of first information comprised in the first MAC CE, whether to perform a first operation; or determining, on the basis of whether the first MAC CE comprises the first information, whether to perform the first operation, wherein the first information is key information related to L1 / L2 triggered mobility (LTM), and the first operation comprises a key update operation and / or a packet data convergence protocol (PDCP) reestablishment operation. The present disclosure reduces the complexity of performing LTM by a terminal and improves the availability of LTM.

Description

Communication methods, terminals, network devices, systems, and storage media Technical Field

[0001] This disclosure relates to the field of communications, and in particular to communication methods, terminals, network devices, systems and storage media. Background Technology

[0002] Layer 1 / L2 Triggered Mobility (LTM) refers to the process by which a network device triggers a cell switch between a primary cell (or cell group) (PCell) and / or a primary secondary cell (PSCell) based on measurements from Layer 1 (L1) and / or Layer 2 (L2). Summary of the Invention

[0003] To reduce the complexity of performing LTM, embodiments of this disclosure provide a communication method, a terminal, a network device, a system, and a storage medium.

[0004] According to a first aspect of the present disclosure, a communication method is provided, the method being executed by a terminal, the method comprising:

[0005] Receives the first Media Access Control Unit (MAC) CE sent by the network device;

[0006] Based on the first information included in the first MAC CE, determine whether to perform the first operation; or

[0007] Based on whether the first MAC CE includes the first information, determine whether to perform the first operation;

[0008] The first information is key information related to triggering LTM mobility at layer 1 or layer 2, and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0009] According to a second aspect of the present disclosure, a communication method is provided, the method being performed by a network device, the method comprising:

[0010] Send a first Media Access Control Unit (MAC CE) to the terminal; wherein, the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or, whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information is key information related to Layer 1 or Layer 2 Triggered Mobility LTM, and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0011] According to a third aspect of the present disclosure, a terminal is provided, comprising:

[0012] The transceiver module is configured to receive the first media access control unit (MAC CE) sent by the network device;

[0013] The processing module is configured to determine whether to perform a first operation based on the first information included in the first MAC CE; or to determine whether to perform a first operation based on whether the first information is included in the first MAC CE; wherein the first information is key information related to triggering mobility LTM at layer 1 or layer 2, and the first operation includes a key update operation and / or a packet data convergence protocol (PDCP) reconstruction operation.

[0014] According to a fourth aspect of the present disclosure, a network device is provided, comprising:

[0015] The transceiver module is configured to send a first media access control unit (MAC CE) to a terminal; wherein the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information being key information related to triggering mobility LTM at layer 1 or layer 2, and the first operation including a key update operation and / or a packet data convergence protocol (PDCP) reconstruction operation.

[0016] According to a fifth aspect of the present disclosure, a terminal is provided, comprising:

[0017] One or more processors;

[0018] The processor is used to execute the method described in any one of the first aspects.

[0019] According to a sixth aspect of the present disclosure, a network device is provided, comprising:

[0020] One or more processors;

[0021] The processor is used to execute the communication method described in any one of the second aspects.

[0022] According to a seventh aspect of the present disclosure, a communication system is provided, comprising:

[0023] A terminal, the terminal being configured to implement the communication method described in any one of the first aspects;

[0024] A network device configured to implement the communication method described in any one of the second aspects.

[0025] According to an eighth aspect of the present disclosure, a storage medium is provided that stores instructions that, when executed on a communication device, cause the communication device to perform a communication method as described in any one of the first or second aspects.

[0026] According to a ninth aspect of the present disclosure, a computer program product is provided, including a computer program that, when executed by a processor, is used to implement the communication method described in any one of the first or second aspects.

[0027] In this embodiment of the disclosure, the terminal can determine whether to perform a first operation based on the first information included in the first MAC CE sent by the network device. The first operation includes, but is not limited to, a key update operation and / or a PDCP reconstruction operation. This reduces the complexity of the terminal performing LTM and improves the availability of LTM.

[0028] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] Figure 1A is a schematic diagram of the structure of a communication system according to an exemplary embodiment.

[0031] Figure 1B is a schematic diagram of a scenario of a dual-connection DC according to an exemplary embodiment.

[0032] Figure 1C is a schematic diagram of an NR-DC architecture according to an exemplary embodiment.

[0033] Figure 1D is a schematic diagram of a key update for an MN according to an exemplary embodiment.

[0034] Figure 2 is an interactive schematic diagram of a communication method according to an exemplary embodiment.

[0035] Figure 3A is a flowchart illustrating one of the communication methods according to an exemplary embodiment.

[0036] Figure 3B is a second schematic flowchart illustrating a communication method according to an exemplary embodiment.

[0037] Figure 4A is a schematic diagram of the structure of a MAC CE according to an exemplary embodiment.

[0038] Figure 4B is a second schematic diagram of a MAC CE structure according to an exemplary embodiment.

[0039] Figure 4C is a third schematic diagram of a MAC CE structure according to an exemplary embodiment.

[0040] Figure 4D-1 is a schematic diagram of the structure of a MAC CE according to an exemplary embodiment.

[0041] Figure 4D-2 is the fifth of a schematic diagram of a MAC CE according to an exemplary embodiment.

[0042] Figure 4E is an interactive schematic diagram illustrating an MCG LTM key update according to an exemplary embodiment.

[0043] Figure 4F is an interactive schematic diagram illustrating an SCG LTM key update according to an exemplary embodiment.

[0044] Figure 5A is a schematic diagram of the structure of a terminal according to an exemplary embodiment.

[0045] Figure 5B is a schematic diagram of the structure of a network device according to an exemplary embodiment.

[0046] Figure 6A is a schematic diagram of the structure of a communication device according to an exemplary embodiment.

[0047] Figure 6B is a schematic diagram of the structure of a chip according to an exemplary embodiment. Detailed Implementation

[0048] This disclosure provides a communication method, terminal, network device, system, and storage medium.

[0049] In a first aspect, embodiments of this disclosure propose a communication method executed by a terminal, the method comprising: receiving a first Media Access Control Unit (MAC CE) sent by a network device; determining whether to perform a first operation based on first information included in the first MAC CE; or determining whether to perform a first operation based on whether the first MAC CE includes the first information; wherein the first information is key information related to Layer 1 / Layer 2 Triggered Mobility Management (LTM), and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0050] In the above embodiments, the terminal can determine whether to perform a first operation based on the first information included in the first MAC CE sent by the network device. The first operation includes, but is not limited to, a key update operation and / or a PDCP reconstruction operation. This reduces the complexity of the terminal performing LTM and improves the availability of LTM.

[0051] In conjunction with some embodiments of the first aspect, in some embodiments, the first information includes any one of the following: indication information, the indication information being used to indicate whether to perform the first operation; the value of a first field, the first field including any one of the following: a next-hop chain counter NCC field; a secondary node security counter sk-counter field based on the initial configuration; a reserved field.

[0052] In the above embodiments, the first information may include any of the above, which reduces the latency for the terminal to determine whether to perform the first operation.

[0053] In conjunction with some embodiments of the first aspect, in some embodiments, the sk-counter field is used to indicate any of the following: the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell; the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node; the change in the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell relative to the value of the sk-counter of the source primary / secondary cell; the change in the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node relative to the value of the sk-counter of the source secondary node.

[0054] In the above embodiments, the sk-counter field can indicate any of the above, thereby allowing the terminal to quickly determine whether to perform the first operation. Furthermore, when the sk-counter field indicates the sk-counter field change amount, signaling overhead can be effectively reduced.

[0055] In conjunction with some embodiments of the first aspect, in some embodiments, determining whether to perform the first operation based on the first information included in the first MAC CE includes at least one of the following: determining whether to perform the first operation based on the value of the first field; determining whether to perform the first operation based on the indication information; determining whether to perform the first operation based on the first identifier and the value of the first field, wherein the first identifier is used to identify the access network device.

[0056] In the above embodiments, the terminal can quickly determine whether to perform the first operation based on the first information, thereby improving the reliability of performing the first operation.

[0057] In conjunction with some embodiments of the first aspect, in some embodiments, determining whether to perform the first operation based on the value of the first field includes any of the following: if the value of the first field is a first value, it is determined not to perform the first operation; if the value of the first field is a second value, it is determined to perform the first operation; if the value of the first field is less than the NCC value corresponding to the source cell, it is determined not to perform the first operation; if the value of the first field is greater than or equal to the NCC value corresponding to the source cell, it is determined to perform the first operation.

[0058] In the above embodiments, the terminal can quickly determine whether to perform the first operation based on the value of the first field. The configuration is simple and the reliability of performing the first operation is improved, ensuring the communication security between the network device and the terminal.

[0059] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes at least one of the following: based on the protocol agreement, when determining that the value of the first field cannot be the first value when performing LTM between centralized units (CUs); based on the protocol agreement, when determining that the value of the first field needs to be updated when performing LTM between CUs; ​​based on the protocol agreement, when determining that vertical key updates are supported when performing LTM between CUs.

[0060] In the above embodiments, the above content can be agreed upon by the protocol to improve the reliability of LTM execution between CUs.

[0061] In conjunction with some embodiments of the first aspect, in some embodiments, the value of the first field is incremented; and / or when the value of the first field reaches its maximum value, it is incremented again from the initial value.

[0062] In the above embodiments, the value of the first field is limited, and the terminal can clearly define the setting method of the first field to ensure that the terminal and the network device have a consistent understanding of the content indicated by the first field.

[0063] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes at least one of the following: if it is determined, based on the first identifier, that the first MAC CE does not include the NCC field; if it is determined, based on the first identifier, that the first MAC CE does not include the sk-counter field; if it is determined, based on the first identifier, that the first MAC CE includes the reserved field, and the value of the reserved field is a first value; if it is determined, based on the first identifier, that the first MAC CE includes the NCC field, and the value of the NCC field is a first value; if it is determined, based on the first identifier, that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a first value; if it is determined, based on the first identifier, that the first MAC CE includes the NCC field, and the value of the NCC field is a second value; if it is determined, based on the first identifier, that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a second value.

[0064] In the above embodiments, after determining whether to perform the first operation based on the first identifier, the terminal can determine whether the first MAC CE includes the first field and / or determine the value of the first field to ensure that the terminal's determination of whether to perform the first operation based on the first identifier and the value of the first field is consistent, thus avoiding misjudgment.

[0065] In conjunction with some embodiments of the first aspect, in some embodiments, determining whether to perform the first operation based on the first identifier and the value of the first field includes any one of the following: if it is determined that the first operation will not be performed based on the first identifier and the value of the first field, then the first operation will not be performed; if it is determined that the first operation will be performed based on the first identifier and the value of the first field, then the first operation will be performed; if it is determined that the first operation will not be performed based on the first identifier, but the value of the first field indicates that the first operation will be performed, then the first operation will be performed; if it is determined that the first operation will be performed based on the first identifier, but the value of the first field indicates that the first operation will not be performed, then the first operation will not be performed.

[0066] In the above embodiments, if there is a conflict between the value of the first identifier and the value of the first field indicating whether to perform the first operation, the terminal can determine whether to perform the first operation based on the value of the first field, thereby improving the reliability of the terminal in determining whether to perform the first operation.

[0067] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes: if it is determined based on the first identifier that the first operation will be performed, but it is determined based on the value of the first field that the first operation will not be performed, sending a notification message to the network device, the notification message being used to notify the network device of a key configuration error.

[0068] In the above embodiments, the terminal can notify the network device of a key configuration error, thereby improving the reliability of key updates and ensuring the security of communication between the terminal and the network device.

[0069] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes any one of the following: if the first identifier of the serving cell is different from the first identifier of the candidate cell, it is determined to perform the first operation; if the first identifier of the serving cell is different from the first identifier of the candidate configuration, it is determined to perform the first operation; if the first identifier of the serving cell is the same as the first identifier of the candidate cell, it is determined not to perform the first operation; if the first identifier of the serving cell is the same as the first identifier of the candidate configuration, it is determined not to perform the first operation.

[0070] In the above embodiments, the terminal can determine whether to perform the first operation based on the first identifier according to any of the above, thereby clarifying the terminal behavior and improving the reliability of the terminal performing LTM.

[0071] In conjunction with some embodiments of the first aspect, in some embodiments, determining whether to perform the first operation based on whether the first information is included in the first MAC CE includes any one of the following: if the first information is included in the first MAC CE, determining to perform the first operation; if the first information is not included in the first MAC CE, determining not to perform the first operation.

[0072] In the above embodiments, the terminal can determine whether to perform the first operation based on whether the first information is included in the first MAC CE, which effectively reduces the signaling overhead of the first MAC CE and reduces the latency of the terminal in determining whether to perform the first operation.

[0073] In conjunction with some embodiments of the first aspect, in some embodiments, the first MAC CE is also used to trigger the terminal to perform LTM cell handover.

[0074] In the above embodiments, the terminal can be triggered to perform LTM cell handover through the first MAC CE, further reducing signaling overhead.

[0075] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes: storing the first information; determining whether to perform the first operation based on the first information includes: receiving a second MAC CE sent by the network device or triggering an LTM cell handover based on an event, and determining whether to perform the first operation based on the stored first information, wherein the second MAC CE is used to trigger the terminal to perform an LTM cell handover.

[0076] In the above embodiments, the terminal can first store the first information, and upon receiving the second MAC CE sent by the network device or upon triggering an LTM cell handover based on an event, determine whether to perform the first operation based on the stored first information, thereby improving the availability of subsequent LTM.

[0077] In conjunction with some embodiments of the first aspect, in some embodiments, when a secondary cell group LTM between SNs is triggered by a secondary node SN, the network device includes any one of the following: a source SN, which obtains the first information from a primary node MN; and MN.

[0078] In the above embodiments, when the SCG LTM between SNs is triggered by the SN, the terminal can obtain the first MAC CE from the source SN or MN, and thus determine whether to perform the first operation based on the first information therein. This clarifies the source of the first information obtained by the terminal and ensures high availability.

[0079] Secondly, embodiments of this disclosure propose a communication method executed by a network device. The method includes: sending a first Media Access Control Unit (MAC CE) to a terminal; wherein the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, wherein the first information is key information related to Layer 1 / Layer 2 Triggered Mobility Management (LTM), and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0080] In conjunction with some embodiments of the second aspect, in some embodiments, the first information includes any one of the following: indication information, the indication information being used to indicate whether to perform the first operation; the value of a first field, the first field including any one of the following: a next-hop chain counter NCC field; a secondary node security counter sk-counter field based on the initial configuration; a reserved field.

[0081] In conjunction with some embodiments of the second aspect, in some embodiments, the sk-counter field is used to indicate any of the following: the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell; the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node; the change in the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell relative to the value of the sk-counter of the source primary / secondary cell; the change in the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node relative to the value of the sk-counter of the source secondary node.

[0082] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes at least one of the following: based on the protocol agreement, when determining that the value of the first field cannot be the first value when performing LTM between centralized units (CUs); based on the protocol agreement, when determining that the value of the first field needs to be updated when performing LTM between CUs; ​​based on the protocol agreement, when determining that vertical key updates are supported when performing LTM between CUs.

[0083] In conjunction with some embodiments of the second aspect, in some embodiments, the value of the first field is incremented; and / or if the value of the first field reaches its maximum value, it is incremented again from the initial value.

[0084] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes: receiving a notification message sent by the terminal when it is determined to perform the first operation based on a first identifier, but determined not to perform the first operation based on the value of the first field, wherein the first identifier is used to identify the access network device, and the notification message is used to notify the network device of a key configuration error.

[0085] In conjunction with some embodiments of the second aspect, in some embodiments, the first MAC CE is also used to trigger the terminal to perform LTM cell handover.

[0086] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes: sending a second MAC CE to the terminal, the second MAC CE being used to trigger the terminal to perform LTM cell handover.

[0087] In conjunction with some embodiments of the second aspect, in some embodiments, when a secondary cell group LTM between SNs is triggered by a secondary node SN, the network device includes any one of the following: a source SN, which obtains the first information from a primary node MN; and MN.

[0088] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes: when the network device includes the source SN, sending a request message to the MN, the request message being used to request an updated key, the request message including an identifier of the target SN; and receiving the first information sent by the MN based on the request message.

[0089] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes: if the network device includes the MN, sending the generated SN key to the target SN.

[0090] Thirdly, embodiments of this disclosure propose a terminal, including: a transceiver module configured to receive a first Media Access Control Unit (MAC CE) sent by a network device; and a processing module configured to determine whether to perform a first operation based on first information included in the first MAC CE; or to determine whether to perform a first operation based on whether the first MAC CE includes the first information; wherein the first information is key information related to Layer 1 / Layer 2 Triggered Mobility Management (LTM), and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0091] Fourthly, embodiments of this disclosure propose a network device, including: a transceiver module configured to send a first Media Access Control Unit (MAC CE) to a terminal; wherein, the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or, whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information being key information related to Layer 1 / Layer 2 Triggered Mobility Management (LTM), and the first operation including a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0092] Fifthly, embodiments of this disclosure provide a terminal comprising: one or more processors; wherein the processors are configured to execute the communication method described in any one of the first aspects.

[0093] In a sixth aspect, embodiments of this disclosure provide a network device comprising: one or more processors; wherein the processors are configured to perform the communication method described in any one of the second aspects.

[0094] In a seventh aspect, embodiments of this disclosure provide a communication system comprising: a terminal configured to perform the communication method described in any one aspect; and a network device configured to perform the communication method described in any one aspect.

[0095] Eighthly, embodiments of this disclosure provide a storage medium storing instructions that, when executed on a communication device, cause the communication device to perform the communication method as described in either the first or second aspect.

[0096] In a ninth aspect, embodiments of this disclosure provide a computer program product, including a computer program that, when executed by a processor, is used to implement the communication method described in any one of the first or second aspects.

[0097] It is understood that the aforementioned terminals, network devices, communication systems, and storage media are all used to execute the methods proposed in the embodiments of this disclosure. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0098] This disclosure provides communication methods, terminals, network devices, systems, and storage media. In some embodiments, the terms "communication method" and "information transmission method," "information processing method," etc., can be used interchangeably; the terms "communication device" and "information transmission device," "information processing device," etc., can be used interchangeably; and the terms "information transmission system," "information processing system," "communication system," etc., can be used interchangeably.

[0099] This disclosure is not exhaustive, but merely illustrative of some embodiments, and is not intended to limit the scope of protection of this disclosure. Unless otherwise specified, each step in a particular embodiment can be implemented as an independent embodiment, and the steps can be arbitrarily combined. For example, a solution after removing some steps in a particular embodiment can also be implemented as an independent embodiment, and the order of the steps in a particular embodiment can be arbitrarily interchanged. Furthermore, the optional implementation methods in a particular embodiment can be arbitrarily combined; moreover, the embodiments can be arbitrarily combined, for example, some or all steps of different embodiments can be arbitrarily combined, and a particular embodiment can be arbitrarily combined with the optional implementation methods of other embodiments.

[0100] In each of the disclosed embodiments, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of the embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0101] The terminology used in the embodiments of this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure.

[0102] In this disclosure, unless otherwise stated, elements expressed in the singular form, such as "a," "an," "the," "the aforementioned," "this," etc., can mean "one and only one," or "one or more," "at least one," etc. For example, when using articles such as "a," "an," "the," etc. in translation, the noun following the article can be understood as either a singular or a plural expression.

[0103] In the embodiments disclosed herein, "multiple" refers to two or more.

[0104] In some embodiments, the terms “at least one of”, “one or more”, “a plurality of”, “multiple”, etc., may be used interchangeably.

[0105] In some embodiments, the notation "at least one of A and B", "A and / or B", "A in one case, B in another", "in response to one case A, in response to another case B", etc., may include the following technical solutions depending on the situation: in some embodiments, A (execute A regardless of B); in some embodiments, B (execute B regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed); in some embodiments, A and B (both A and B are executed). The same applies when there are more branches such as A, B, C, etc.

[0106] In some embodiments, the notation "A or B" may include the following technical solutions, depending on the situation: in some embodiments, A (execution of A regardless of B); in some embodiments, B (execution of B regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed). The same applies when there are more branches such as A, B, C, etc.

[0107] The prefixes "first," "second," etc., used in the embodiments of this disclosure are merely for distinguishing different descriptive objects and do not impose restrictions on the position, order, priority, quantity, or content of the descriptive objects. The description of the descriptive objects is found in the claims or the context of the embodiments, and the use of prefixes should not constitute unnecessary restrictions. For example, if the descriptive object is a "field," the ordinal numbers preceding "field" in "first field" and "second field" do not restrict the position or order of the "fields." "First" and "second" do not restrict whether the "fields" they modify are in the same message, nor do they restrict the order of "first field" and "second field." Similarly, if the descriptive object is a "level," the ordinal numbers preceding "level" in "first level" and "second level" do not restrict the priority between "levels." Furthermore, the number of descriptive objects is not limited by ordinal numbers and can be one or more. For example, in "first device," the number of "devices" can be one or more. Furthermore, the objects modified by different prefixes can be the same or different. For example, if the object being described is "device", then "first device" and "second device" can be the same device or different devices, and their types can be the same or different. Similarly, if the object being described is "information", then "first information" and "second information" can be the same information or different information, and their content can be the same or different.

[0108] In some embodiments, “including A,” “containing A,” “for indicating A,” and “carrying A” can be interpreted as directly carrying A or indirectly indicating A.

[0109] In some embodiments, the apparatus and device may be interpreted as physical or virtual, and their names are not limited to those described in the embodiments. In some cases, they may also be understood as "equipment", "device", "circuit", "network element", "node", "function", "unit", "section", "system", "network", "entity", "body", etc.

[0110] In some embodiments, the acquisition of data, information, etc., may comply with the laws and regulations of the country where the location is situated.

[0111] In some embodiments, data, information, etc., may be obtained with the user's consent.

[0112] Furthermore, each element, each row, or each column in the table of this disclosure can be implemented as an independent embodiment, and any combination of any element, any row, or any column can also be implemented as an independent embodiment.

[0113] Figure 1A is a schematic diagram of the architecture of a communication system according to an embodiment of the present disclosure.

[0114] As shown in Figure 1A, the communication system 100 includes a terminal 101 and a network device 102.

[0115] In some embodiments, terminal 101 includes, for example, at least one of the following: mobile phone, wearable device, Internet of Things device, car with communication function, smart car, tablet computer, computer with wireless transceiver function, virtual reality (VR) terminal device, augmented reality (AR) terminal device, wireless terminal device in industrial control, wireless terminal device in self-driving, wireless terminal device in remote medical surgery, wireless terminal device in smart grid, wireless terminal device in transportation safety, wireless terminal device in smart city, and wireless terminal device in smart home, but is not limited thereto.

[0116] In some embodiments, network device 102 may include at least one of access network device 102-1 and core network device 102-2.

[0117] In some embodiments, the access network device 102-1 is, for example, a node or device that connects a terminal to a wireless network. The access network device may include at least one of the following in a 5G communication system: an evolved Node B (eNB), a next-generation eNB (ng-eNB), a next-generation Node B (gNB), a node B (NB), a home node B (HNB), a home evolved node B (HeNB), a wireless backhaul device, a radio network controller (RNC), a base station controller (BSC), a base transceiver station (BTS), a base band unit (BBU), a mobile switching center, a base station in a 6G communication system, an open RAN, a cloud RAN, a base station in other communication systems, and an access node in a Wi-Fi system, but is not limited thereto.

[0118] In some embodiments, the technical solutions of this disclosure can be applied to the Open RAN architecture. In this case, the interfaces between or within access network devices involved in the embodiments of this disclosure can be transformed into internal interfaces of Open RAN. The processes and information interactions between these internal interfaces can be implemented by software or programs.

[0119] In some embodiments, the access network device 102-2 may be composed of a central unit (CU) and a distributed unit (DU). The CU may also be called a control unit. By adopting the CU-DU structure, the protocol layer of the access network device can be separated. Some of the protocol layer functions are centrally controlled by the CU, while the remaining part or all of the protocol layer functions are distributed in the DU, which is centrally controlled by the CU. However, this is not the only possibility.

[0120] In some embodiments, the core network device 102-2 may be a single device, including a first network element, a second network element, etc., or it may be multiple devices or a group of devices, each including all or part of the first network element, the second network element, etc. Network elements may be virtual or physical. The core network may include, for example, at least one of the Evolved Packet Core (EPC), 5G Core Network (5GCN), and Next Generation Core (NGC).

[0121] It is understood that the communication system described in this disclosure is for the purpose of more clearly illustrating the technical solutions of this disclosure, and does not constitute a limitation on the technical solutions proposed in this disclosure. As those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions proposed in this disclosure are also applicable to similar technical problems.

[0122] The following embodiments of this disclosure can be applied to the communication system 100 shown in FIG1A, or to some of the main bodies, but are not limited thereto. The main bodies shown in FIG1A are illustrative. The communication system may include all or some of the main bodies in FIG1A, or it may include other main bodies outside of FIG1A. The number and form of each main body are arbitrary. Each main body may be physical or virtual. The connection relationship between the main bodies is illustrative. The main bodies may not be connected or may be connected. The connection can be in any way, it can be a direct connection or an indirect connection, it can be a wired connection or a wireless connection.

[0123] The embodiments disclosed herein can be applied to Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 5G new radio (NR), Future Radio Access (FRA), New-Radio Access Technology (RAT), New Radio (NR), New radio access (NX), Future generation radio access (FX), Global System for Mobile communications (GSM), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), and IEEE 802.20, Ultra-Wideband (UWB), Bluetooth (a registered trademark), Public Land Mobile Network (PLMN) networks, Device-to-Device (D2D) systems, Machine-to-Machine (M2M) systems, Internet of Things (IoT) systems, Vehicle-to-Everything (V2X) systems, systems utilizing other communication methods, and next-generation systems built upon them, etc. Furthermore, multiple systems can be combined (e.g., a combination of LTE or LTE-A with 5G).

[0124] In some embodiments, the relevant scenarios will be introduced first.

[0125] Dual Connectivity (DC):

[0126] 5G systems employ a DC architecture, comprising two cell (or cell group) groups:

[0127] The Master Cell Group (MCG) corresponds to the Master Node (MN) on the network side.

[0128] Secondary Cell Group (SCG) corresponds to a secondary node (SN) on the network side.

[0129] The MCG consists of one PCell and one or more secondary cells (or cell groups). The SCG consists of one PSCell and one or more SCells. The PCell and PSCell can be collectively referred to as special cells (or cell groups).

[0130] Within the MCG, there is a cell used to initiate initial access; this cell is called the PCell. As the name suggests, the PCell is the most "primary" cell in the MCG. The PCell in the MCG and the SCell in the MCG are combined through Carrier Aggregation (CA). In the MCG, the primary cell is the PCell, and the secondary cell is the SCell; in the SCG, the primary and secondary cells are the PSCell, and the secondary cell is the SCell. Because much signaling is only transmitted on the PCell and PSCell, for ease of description, the protocol also defines a concept called sPCell, where the PCell and PSCell are collectively referred to as sPCell. A schematic diagram of a DC scenario is shown in Figure 1B.

[0131] Next-generation radio access networks (NG-RAN) support dual connectivity NR-NR DC (NR-DC), where a terminal connects to one base station gNB acting as the MN and another gNB acting as the SN. The primary gNB connects to the 5G core network (5GC) via the NG interface, and the two gNBs connect to each other via the Xn interface. The secondary gNB can also connect to the 5GC via the NG-U interface. Furthermore, NR-DC can also be used for a terminal to access a single gNB, acting as both the MN and SN, and simultaneously configuring both the MCG and SCG. An NR-DC architecture can be illustrated as shown in Figure 1C.

[0132] LTM:

[0133] LTM refers to a process in which a network device triggers a cell switch (PCell and / or PSCell) based on L1 measurement results through the Media Access Control-Control Element (MAC CE), which may be accompanied by changes in the MCG and / or SCG.

[0134] In this process, the gNB receives an L1 measurement report from the terminal. Based on this report, the gNB changes the terminal's serving cell via a cell switch command issued by the MAC CE. The cell switch command indicates an LTM candidate cell configuration that the gNB has pre-provided to the terminal via Radio Resource Control (RRC) signaling. The terminal then accesses the target cell indicated in the cell switch command based on the received cell switch command. LTM can be used to reduce mobility latency.

[0135] In this context, LTM candidate cell configurations can only be added, modified, and released by network devices via RRC signaling. The LTM process can be used to reduce mobility latency.

[0136] For LTM, subsequent LTMs can be supported. Subsequent LTMs mean that after a mobility operation is performed, the terminal will not delete the LTM configuration information on its own. The LTM configuration information can continue to be used to trigger subsequent LTMs even if RRC reconfiguration and updates are not performed.

[0137] MN's key update during the handover process:

[0138] The key update process is shown in Figure 1D. When the Next Hop Chaining Counter (NCC) field is 0, K... gNB As the initial value, K increases with the value of the NCC field. gNB A new K can be generated based on the next hop (NH) information, physical cell identifier (PCI), and downlink frequency provided by the network side. gNB .

[0139] Among them, K gNB It is a key used for secure communication between terminals and network devices. In the event of a change in the serving gNB, K... gNB And so it changed.

[0140] LTM version 18 (Release-18, Rel-18) does not involve inter-gNB LTM, so K does not need to be updated during Rel-18 LTM-supported cell switching. gNB Because the service gNB has not changed, the original K gNB It can be used in different candidate cells, but the gNB Key update indicator (masterKeyUpdate) is not included in the Rel-18 MCG LTM candidate configuration.

[0141] In the inter-gNB LTM of version 19 (Release-19, Rel-19), if the key processing scheme in Rel-18 MCG LTM is continued, the terminal will use the same security key before and after executing inter-gNB LTM, resulting in a security key reuse problem.

[0142] In some embodiments, instructing the terminal whether to perform a key update via separate signaling increases the complexity of the terminal performing the LTM. To reduce the complexity of the terminal performing the LTM and improve its availability, this disclosure provides the following communication methods, terminals, network devices, systems, and storage media.

[0143] Figure 2 is an interactive schematic diagram of a communication method according to an embodiment of the present disclosure. As shown in Figure 2, the embodiments of the present disclosure relate to a communication method, which includes:

[0144] In step S2101, network device 102 sends a first MAC CE to terminal 101.

[0145] In some embodiments, terminal 101 receives a first MAC CE.

[0146] In some embodiments, the first MAC CE may include first information, which is key information related to the LTM.

[0147] In one example, the first information can be used by terminal 101 to determine whether to perform the first operation.

[0148] In one example, the first operation includes, but is not limited to, at least one of the following: key update operation; Packet Data Convergence Protocol (PDCP) reconstruction operation.

[0149] For example, the key update operation includes, but is not limited to, updating K. gNB Among them, K gNBIt is a key used for secure communication between terminals and network devices. In the event of a change in the serving gNB, K... gNB And so it changed.

[0150] For example, a PDCP reconstruction operation can also be called a "PDCP entity reconstruction operation", which may include requesting encryption algorithms and key values ​​from higher layers, and / or requesting integrity protection from higher layers, etc.

[0151] The name of the first operation is not limited and can be interchanged with "key update operation", "key related operation", "PDCP reconstruction operation", "PDCP entity reconstruction operation", etc.

[0152] In some embodiments, the first MAC CE may include first information or may not include first information, and the terminal 101 determines whether to perform the first operation based on whether the first information is included.

[0153] In some embodiments, the first information may include, but is not limited to, any of the following: indication information; the value of the first field.

[0154] In one example, the indication information can be used to indicate whether to perform the first operation.

[0155] For example, the indication information is set to "true" and can be used to instruct the execution of the first operation.

[0156] For example, the indication information is set to "false", which can be used to indicate that the first operation should not be performed.

[0157] For example, the indication information can occupy 1 bit, with the bit value set to a specific value, such as "1", to indicate that the first operation is performed, and the bit value set to another specific value, such as "0", to indicate that the first operation is not performed. The reverse is also true.

[0158] For example, if the first MAC CE includes indication information, the structure of the first MAC CE can be as shown in Figure 4A, where field E can be used to represent the indication information.

[0159] The above is merely an illustrative example, and this disclosure does not limit the structure of the first MAC CE including indication information.

[0160] In one example, the first field includes any of the following: an NCC field; a secondary node security counter sk-counter field based on the initial configuration; or a reserved field.

[0161] For example, if the LTM is an MCG LTM, the first field can be an NCC field or a reserved field.

[0162] For example, if the first MAC CE includes a first field, and the first field is an NCC field, the structure of the first MAC CE can be as shown in Figure 4B.

[0163] For example, the first MAC CE includes a first field. If the first field is a reserved field, the structure of the first MAC CE can be as shown in Figure 4C.

[0164] For example, if the LTM is an SCG LTM, then the first field can be an sk-counter field or a reserved field.

[0165] The sk-counter field can be used to indicate any of the following: the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell; the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node; the change in the value of the sk-counter corresponding to the target primary / secondary cell and / or candidate primary / secondary cell relative to the value of the sk-counter of the source primary / secondary cell; or the change in the value of the sk-counter corresponding to the target secondary node and / or candidate secondary node relative to the value of the sk-counter of the source secondary node.

[0166] The change in the value of the sk-counter corresponding to the target primary / secondary cell and / or the candidate primary / secondary cell relative to the value of the sk-counter of the source primary / secondary cell can be the increment of the value of the sk-counter corresponding to the target primary / secondary cell and / or the candidate primary / secondary cell relative to the value of the sk-counter of the source primary / secondary cell.

[0167] The change in the value of the sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node relative to the value of the sk-counter of the source auxiliary node can be the increment of the value of the sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node relative to the value of the sk-counter of the source auxiliary node.

[0168] Understandably, considering that the maximum value of sk-counter can be 65535, indicating its specific value through the sk-counter field might consume a large amount of signaling resources, leading to unnecessary signaling overhead. Therefore, the sk-counter field can be used to indicate the change in the value of the aforementioned sk-counter, thereby reducing signaling overhead.

[0169] The above is merely an illustrative example. This disclosure does not limit whether the sk-counter field indicates a specific value of sk-counter or the amount of change in the value of sk-counter.

[0170] In some embodiments, the first MAC CE can also be used to trigger the terminal 101 to perform LTM cell handover.

[0171] That is, the first MAC CE is the LTM cell handover command MAC CE, which includes first information, which can be used by terminal 101 to determine whether to perform the first operation.

[0172] In some embodiments, the first MAC CE may be used only by the terminal 101 to determine whether to perform the first operation, that is, the terminal 101 may be triggered to perform LTM cell handover by other MAC CEs, such as the second MAC CE.

[0173] In one example, after receiving the first information, terminal 101 can store the first information. Subsequently, based on the second MAC CE sent by network device 102 or the LTM cell handover triggered by an event, it can determine whether to perform the first operation.

[0174] In some embodiments, for SCG LTM, especially inter-SN SCG LTM triggered by SN, network device 102 may include, but is not limited to, source SN and / or MN.

[0175] In one example, when network device 102 is the source SN, the source SN can obtain the first information from the MN. Furthermore, the source SN can send a first MAC CE to terminal 101, which includes the first information.

[0176] For example, the source SN can send a request message to the MN before triggering the inter-SN SCG LTM. This request message is used to request the updated key, that is, to request the execution of the key update.

[0177] Optionally, the request message may include an identifier of the target SN.

[0178] After receiving the request message, the MN can generate the key for the SN and send it to the target SN. Additionally, it can send initial information, such as the value or change of the sk-counter, to the source MN, which then transmits it to the terminal 101 via the first MAC CE.

[0179] In one example, if network device 102 is an MN, the MN can directly send the first MAC CE to terminal 101, which includes the first information. Of course, the MN can generate the key of the SN and send it to the target SN.

[0180] In some embodiments, when the network device 102 triggers the terminal 101 to perform LTM cell handover, it sends a first MAC CE to the terminal.

[0181] In some embodiments, when the network device 102 needs to inform the terminal 101 whether to perform the first operation, it sends a first MAC CE to the terminal.

[0182] In some embodiments, network device 102 sends a first MAC CE to terminal when the key is updated and / or terminal 101 needs to perform PDCP reconstruction.

[0183] In some embodiments, network device 102 may send a first MAC CE to terminal 101 based on a request from terminal 101.

[0184] In some embodiments, network device 102 sends a first MAC CE to the terminal when the MCG LTM key is updated.

[0185] In some embodiments, network device 102 sends a first MAC CE to the terminal when the SCG LTM key is updated.

[0186] The above is merely an illustrative example, and this disclosure does not limit the timing or event that triggers the network device 102 to send the first MAC CE to the terminal.

[0187] In some embodiments, the first MAC CE may include one or more of the following:

[0188] The first type of first MAC CE can refer to a MAC CE that includes an NCC (or NCC value) for triggering an LTM cell switch, such as an Enhanced LTM Cell Switch Command MAC CE.

[0189] For example, the first type of first MAC CE can be as shown in Figure 4D-1, where the NCC field in Oct8 is used to indicate the value of the NCC corresponding to the LTM target configuration ID (or LTM candidate configuration ID, or LTM candidate cell, or LTM target cell) indicated in Oct1.

[0190] This NCC field can also be referred to as the NCC value field, and this disclosure does not limit it.

[0191] In this example, the position of the NCC field is not limited in this disclosure; Figure 4D-1 is merely an example. For instance, NCC may correspond to a separate row, which can be placed in any position, not limited to row 8 in Figure 4D-1. In this row, NCC can be placed in any three consecutive bits out of the eight bits in that row, with the other positions reserved.

[0192] The second type of first MAC CE can refer to a MAC CE used to trigger an LTM Cell Switch that does not contain an NCC (or NCC value), such as an LTM Cell Switch Command MAC CE.

[0193] For example, the first type of first MAC CE and the second type of first MAC CE are different MAC CEs. For instance, the first type of first MAC CE is an Enhanced LTM Cell Switch Command MAC CE; the second type of first MAC CE is an LTM Cell Switch Command MAC CE.

[0194] The above is merely an illustrative example, and this disclosure does not limit the type of the first MAC CE.

[0195] In some embodiments, the first MAC CE may include one or more of the following:

[0196] The first MAC CE can be a first type of first MAC CE, wherein the first type of first MAC CE is a MAC CE containing NCC (or NCC value) used to trigger LTM Cell Switch.

[0197] Alternatively, the first MAC CE can be a second type of first MAC CE, wherein the second type of first MAC CE is a MAC CE for triggering LTM Cell Switch that does not include NCC (or NCC value).

[0198] For example, a first type of first MAC CE and a second type of first MAC CE can be represented by the same MAC CE format, through which the MAC CE contains indication information to indicate whether the MAC CE is a first type of first MAC CE and / or whether it is a second type of first MAC CE.

[0199] For example, if the indication information is a specific value, such as 1, it indicates that the first MAC CE is a first type of first MAC CE. In this case, this MAC CE contains a specific octet (or byte) (or octet) containing an NCC (or NCC value).

[0200] For example, if the indication information is a specific value, such as 0, it indicates that the first MAC CE is a third type of first MAC CE. For example, in this case, this MAC CE does not contain a specific octet (or byte) (i.e., Oct) that is used to contain the NCC. That is, the first MAC CE does not contain the NCC at this time. For example, as shown in Figure 4D-2.

[0201] For example, the first E / R bit in Oct3 is the indication information. It is used to indicate whether the MAC CE in Figure 4D-2 is a first type of first MAC CE and / or a second type of first MAC CE.

[0202] For example, if the indication information (E / R bit) indicates that it is the first type of first MAC (the value of the indication information is E (e.g., E=1)), then this MAC CE contains eight bits (Oct8), and Otc8 contains the NCC field.

[0203] For example, the NCC field is used to indicate the NCC value corresponding to the LTM target configuration ID (or LTM candidate configuration ID, or LTM candidate cell, or LTM target cell) indicated in Oct1. This NCC field can also be referred to as the NCC value field, and this disclosure does not limit it.

[0204] For example, if the indication information (E / R bit) indicates that it is a second type of first MAC (the value of the indication information is R (e.g., R is 0)), then this MAC CE does not contain Oct8.

[0205] In this example, the position of the NCC field is not limited in this disclosure; Figure 4D-2 is merely an example. For instance, NCC may correspond to a separate row, which can be placed in any position, not limited to row 8 in Figure 4D-2. In this row, NCC can be placed in any three consecutive bits out of the eight bits in that row, with the other positions reserved.

[0206] The above is merely an illustrative example, and this disclosure does not limit the type of the first MAC CE.

[0207] In step S2102, network device 102 sends a second MAC CE to terminal 101.

[0208] In some embodiments, terminal 101 receives a second MAC CE.

[0209] In some embodiments, the second MAC CE is used to trigger the terminal to perform LTM cell handover.

[0210] In some embodiments, the second MAC CE is an LTM cell handover command MAC CE.

[0211] In some embodiments, when it is necessary to trigger terminal 101 to perform LTM cell handover, network device 102 sends a second MAC CE to terminal 101.

[0212] In some embodiments, network device 102 sends a second MAC CE to terminal 101 when LTM cell handover is performed.

[0213] The above is merely an illustrative example, and this disclosure does not limit the timing or event that triggers the network device 102 to send a second MAC CE to the terminal.

[0214] In some embodiments, step S2102 is an optional execution step. For example, if the first MAC CE is used to trigger terminal 101 to perform LTM cell handover, step S2102 may not be executed.

[0215] In step S2103, terminal 101 determines whether to perform the first operation.

[0216] In some embodiments, after receiving the first MAC CE, the terminal 101 may determine whether to perform the first operation based on the first information.

[0217] In some embodiments, after receiving the first MAC CE, the terminal 101 may store the first information, and after receiving the second MAC CE sent by the network device 102, determine whether to perform the first operation based on the stored first information.

[0218] In some embodiments, terminal 101 may determine whether to perform the first operation based on the first information in the following manner:

[0219] Method 1: Determine whether to perform the first operation based on the value of the first field.

[0220] In one example, if the value of the first field is the first value, then terminal 101 can determine that the first operation will not be performed during the execution of LTM.

[0221] The first value can be "0", or it can be other specific values ​​such as "1", which is not limited in this disclosure.

[0222] For example, for MCG LTM, the first field can be an NCC field or a reserved field.

[0223] For MCG LTM, if the value of the NCC field is 0, then terminal 101 can determine that the first operation will not be performed during the execution of MCG LTM.

[0224] For MCG LTM, if the first MAC CE does not include the NCC field, and the first field is replaced by a reserved bit, that is, the first field includes a reserved field, and the value of the reserved field is 0, then terminal 101 can determine that the first operation will not be performed during the execution of MCG LTM.

[0225] It should be noted that for MCG LTM, the first field cannot be the first value when LTM is performed between central units (CUs) by agreement of the protocol. That is, if LTM is performed across CUs, the first operation needs to be performed, and the value of the first field cannot be 0.

[0226] The LTM between CUs can be an LTM between nodes or an LTM between base stations; this disclosure does not limit this.

[0227] Alternatively, the protocol can stipulate that when performing LTM between CUs, the value of the first field needs to be updated. That is, if LTM is performed across CUs, the first operation needs to be performed, and the value of the first field needs to be updated. After the update, the value of the first field cannot be 0.

[0228] The first field can be 0 when initialized, but in other cases, if LTM is performed between CUs, the value of the first field cannot be 0.

[0229] Alternatively, the protocol can be configured to support vertical key updates when performing LTM between CUs. In the case of a vertical key update, the value of the first field will be updated.

[0230] For example, for SCG LTM, the first field can be an sk-counter field or a reserved field.

[0231] For SCG LTM, if the value of the sk-counter field is 0 or the change is 0, then terminal 101 can determine that the first operation will not be performed during the execution of SCG LTM.

[0232] For SCG LTM, if the first MAC CE does not include the sk-counter field, and the first field is replaced by a reserved bit, that is, the first field includes a reserved field with a value of 0, then terminal 101 can determine that the first operation will not be performed during the execution of SCG LTM.

[0233] In one example, if the first field takes the second value, then terminal 101 can determine that the first operation is performed during the LTM process.

[0234] The second value can be "1", or the first value can be other specific values ​​such as "0", which is not limited in this disclosure.

[0235] For example, for MCG LTM, the first field can be an NCC field or a reserved field.

[0236] For MCG LTM, if the NCC field is 1, then terminal 101 can determine that the first operation is performed during the execution of MCG LTM.

[0237] For MCG LTM, if the first MAC CE does not include the NCC field, then the first MAC CE may include a reserved field. If the value of the reserved field is 1, then terminal 101 can determine that the first operation is performed during the execution of MCG LTM.

[0238] For example, for SCG LTM, the first field can be an sk-counter field or a reserved field.

[0239] For SCG LTM, if the sk-counter field is 1, then terminal 101 can determine that the first operation is to be performed during the execution of SCG LTM.

[0240] For SCG LTM, if the first MAC CE does not include the sk-counter field, then the first MAC CE includes a reserved field with a value of 1. In this case, terminal 101 can determine that the first operation is to be performed during the execution of SCG LTM.

[0241] In one example, if the value of the first field is less than the NCC value corresponding to the source cell, the terminal 101 can determine that the first operation will not be performed during the LTM process.

[0242] In one example, if the value of the first field is greater than or equal to the NCC value corresponding to the source cell, then terminal 101 can determine that the first operation is to be performed during the LTM process.

[0243] Understandably, the protocol can stipulate that the value of the first field is incremented. If the value of the first field reaches its maximum value, the value of the first field can be incremented again from its initial value.

[0244] For example, if the value of the NCC field reaches its maximum value, network device 102 can update the Authentication Management Function (AMF) key, instruct terminal 101 to perform an AMF key update, and generate a new initial key based on the updated key_AMF. gNB , where K gNB It can also be called the NG-RAN key (key_NG-RAN) or the MN key (key_MN). The NCC field value is incremented starting from the initial value.

[0245] For example, if the value of the sk-counter field reaches the maximum value of 65535, the value of the sk-counter field can be incremented again from the initial value.

[0246] Method 2: Based on the instruction information, determine whether to perform the first operation.

[0247] In one example, for MCG LTM, if the indication information is set to "true" or the bit value is a specific value such as "1", terminal 101 determines that a first operation needs to be performed during the execution of MCG LTM.

[0248] In one example, for MCG LTM, if the indication information is set to "false" or the bit value is another specific value such as "0", terminal 101 determines that the first operation does not need to be performed during the execution of MCG LTM.

[0249] In one example, for SCG LTM, if the indication information is set to "true" or the bit value is a specific value such as "1", terminal 101 determines that a first operation needs to be performed during the execution of SCG LTM.

[0250] In one example, for SCG LTM, if the indication information is set to "false" or the bit value is another specific value such as "0", terminal 101 determines that the first operation does not need to be performed during the execution of SCG LTM.

[0251] Method 3: Based on the value of the first identifier and the first field, determine whether to perform the first operation.

[0252] In one example, the first identifier can be used to identify the access network device.

[0253] In one example, the first identifier can be configured by network device 102 via RRRC signaling for terminal 101. The first identifier of the serving cell and the first identifier of the candidate cell or candidate configuration can correspond to different RRC field names. Terminal 101 obtains the first identifier of the serving cell and the first identifier of the candidate cell or candidate configuration through the corresponding RRC fields.

[0254] In one example, terminal 101 may determine whether to perform the first operation based on the first identifier.

[0255] For example, if the first identifier of the serving cell and the first identifier of the candidate cell are different, the terminal 101 determines to perform the first operation.

[0256] For example, if the first identifier of the serving cell is different from the first identifier of the candidate configuration, the terminal 101 determines to perform the first operation.

[0257] For example, if the first identifier of the serving cell and the first identifier of the candidate cell are the same, the terminal 101 determines not to perform the first operation.

[0258] For example, if the first identifier of the serving cell is the same as the first identifier of the candidate configuration, the terminal 101 determines not to perform the first operation.

[0259] For MCG LTM:

[0260] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 may determine that the NCC field is not included in the first MAC CE.

[0261] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 can determine that the first MAC CE includes a reserved field, and the value of the reserved field is a first value, such as "0". That is, the reserved field also indicates that the first operation will not be performed.

[0262] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 may determine that the first MAC CE includes the NCC field, and the value of the NCC field is a first value, that is, the NCC field is also used to indicate that the first operation will not be performed.

[0263] In one example, when the first operation is determined to be performed based on the first identifier, terminal 101 can determine that the first MAC CE includes the NCC field, and the value of the NCC field is a second value, that is, the NCC field is also used to indicate the execution of the first operation.

[0264] In one example, when the first operation is determined to be performed based on the first identifier, terminal 101 can determine that the first MAC CE includes a reserved field, and the value of the reserved field is a second value, that is, the reserved field is also used to indicate the execution of the first operation.

[0265] For SCG LTM:

[0266] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 may determine that the sk-counter field is not included in the first MAC CE.

[0267] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 can determine that the first MAC CE includes a reserved field, and the value of the reserved field is a first value, such as "0". That is, the reserved field also indicates that the first operation will not be performed.

[0268] In one example, if it is determined that the first operation will not be performed based on the first identifier, terminal 101 may determine that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a first value, that is, the sk-counter field is also used to indicate that the first operation will not be performed.

[0269] In one example, when the execution of the first operation is determined based on the first identifier, terminal 101 can determine that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a second value, which is different from the first value, i.e., the second value is not 0. If the first field indicates a transformation quantity, the value can be 1 or other values ​​greater than 1. That is, the sk-counter field is also used to indicate the execution of the first operation.

[0270] In one example, when the first operation is determined to be performed based on the first identifier, terminal 101 can determine that the first MAC CE includes a reserved field, and the value of the reserved field is a second value, that is, the reserved field is also used to indicate the execution of the first operation.

[0271] In one example, the above limitations may not be applied, and the determination of whether to perform the first operation may be based on the values ​​of the first identifier and the first word field, respectively. The specific process has been described in the foregoing embodiments and will not be repeated here.

[0272] Furthermore, if it is determined that the first operation will not be performed based on the first identifier, and it is also determined that the first operation will not be performed based on the value of the first field, the terminal 101 may determine that the first operation will not be performed.

[0273] If the first operation is determined to be executed based on the first identifier, and the first operation is determined to be executed based on the value of the first field, then terminal 101 can determine to execute the first operation.

[0274] When the two conflict, terminal 101 may prioritize the value of the first field to determine whether to perform the first operation.

[0275] For example, if it is determined not to perform the first operation based on the first identifier, but to perform the first operation based on the value of the first field, the terminal 101 can determine to perform the first operation.

[0276] For example, if the first identifier of the serving cell is the same as the first identifier of the candidate cell (or candidate configuration), but the first MAC CE includes a first field and the value of the first field is a second value, then the terminal 101 can determine that the first operation needs to be performed during the LTM process.

[0277] For example, if the terminal 101 determines not to execute the first operation based on the first identifier, but determines not to execute the first operation based on the value of the first field, the terminal 101 may determine not to execute the first operation.

[0278] For example, if the first identifier of the serving cell is different from the first identifier of the candidate cell (or candidate configuration), and the first MAC CE does not include the first field, or although it includes the first field, the value of the first field is the first value, the terminal 101 can determine that it will not perform the first operation.

[0279] Accordingly, at this time, terminal 101 can send a notification message to network device 102, which is used to notify network device 102 of a key configuration error.

[0280] Method 4: Based on the first identifier and the type of the received first MAC CE, determine whether to perform the first operation.

[0281] In one example, the first identifier can be configured by network device 102 via an RRC message. The network device can configure corresponding first identifiers for the serving cell and the candidate cell respectively (the first identifier of the serving cell and the first identifier of the candidate cell can correspond to different RRC field names).

[0282] In one example, at least one of the following can be agreed upon by the protocol:

[0283] If the first identifier of the serving cell and the first identifier of the candidate cell are the same, the network device 102 can only send the second type of first MAC CE to the terminal 101, such as the LTM Cell Switch Command MAC CE (LTM Cell Switch Command MAC CE) that does not contain NCC.

[0284] If the first identifier of the serving cell and the first identifier of the candidate cell are different, the network device 102 can only send the first type of first MAC CE to the terminal 101, such as the LTM switch command MAC CE containing NCC (Enhanced LTM Cell Switch Command MAC CE).

[0285] In one example, if the first identifier of the serving cell is the same as the first identifier of the candidate cell, but the network device 102 sends the first type of first MAC CE, then the terminal 101 performs a first operation, such as performing a key update and / or PDCP reconstruction operation.

[0286] In one example, if the first identifier of the serving cell differs from the first identifier of the candidate cell, but network device 102 sends a second type of first MAC CE, then terminal 101 does not perform the first operation, such as not performing key update and / or PDCP reconstruction operations. Accordingly, terminal 101 can send a notification message to network device 102, notifying the network device of a key configuration error.

[0287] In some embodiments, before receiving the LTM cell handover command MAC CE (i.e., the second MAC CE), the terminal 101 may store the first information in the first MAC CE. Upon receiving the second MAC CE or in the case of LMT cell handover triggered based on an event (or failure recovery, etc.), if the first identifier of the serving cell is the same as the first identifier of the candidate cell (or candidate configuration), the terminal 101 does not perform the first operation, that is, it does not perform the key update operation and / or PDCP reconstruction operation.

[0288] In some embodiments, the first MAC CE does not include a first field. If the first identifier of the serving cell and the first identifier of the candidate cell (or candidate configuration) are different, the terminal 101 performs a first operation based on the stored first information, namely, performing a key update operation and / or a PDCP reconstruction operation. For example, for MCG LTM, the terminal 101 may perform the first operation based on the stored NCC value; for SCG LTM, the terminal 101 may perform the first operation based on the stored sk-counter value or change.

[0289] In some embodiments, after receiving the first MAC CE, the terminal 101 may determine whether to perform the first operation based on whether the first MAC CE includes first information.

[0290] In one example, if the first MAC CE includes first information, then terminal 101 determines to perform the first operation.

[0291] In one example, if the first information is not included in the first MAC CE, then terminal 101 determines not to perform the first operation.

[0292] For example, a first MAC CE containing first information and a first MAC CE not containing first information correspond to different types of MAC CEs. As described in the foregoing embodiments, a first MAC CE containing first information and a first MAC CE not containing first information correspond to a first type of first MAC CE and a second type of first MAC CE, respectively; for example, Enhanced LTM Cell Switch Command MAC CE and LTM Cell Switch Command MAC CE, the specific details of which will not be repeated here.

[0293] In step S2104, terminal 101 performs the first operation.

[0294] In some embodiments, terminal 101 performs a first operation when it determines that a first operation needs to be performed.

[0295] In some embodiments, the terminal is based on the current K gNB The updated key is determined by either NH or the value of the first field in the first MAC CE. Specifically, if the value of the NCC field is equal to the current K... gNB The corresponding NCC value allows terminal 101 to base its decision on the current K value. gNB Generate a new K based on the value of the NCC field. gNB If the value of NCC is not equal to the current K. gNB Based on the corresponding NCC value, terminal 101 can generate a new K according to the value of the NCC field and the corresponding NH. gNB And perform PDCP reconstruction operation.

[0296] In one example, terminal 101 can determine the SN key of the target candidate cell based on the value of sk-counter and the key of MN, thereby performing key update operation and / or PDCP reconstruction operation.

[0297] In one example, terminal 101 can determine a new sk-counter based on the increment of the sk-counter, and then determine the SN key of the target candidate cell based on the value of the sk-counter and the key of the MN, and perform key update operation and / or PDCP reconstruction operation.

[0298] In some embodiments, this disclosure does not limit the manner in which the terminal 101 performs the first operation.

[0299] In some embodiments, step S2104 is an optional execution step. For example, if it is determined in step S2103 that the first operation will not be performed, step S2104 may not be performed.

[0300] In some embodiments, the names of information, etc., are not limited to the names described in the embodiments. Terms such as "information", "message", "signal", "signaling", "report", "configuration", "indication", "instruction", "command", "channel", "parameter", "domain", "field", "symbol", "symbol", "codebook", "codeword", "codepoint", "bit", "data", "program", and "chip" can be used interchangeably.

[0301] In some embodiments, terms such as “send,” “transmit,” “report,” “distribute,” “transfer,” “bidirectional transmission,” “send and / or receive” can be used interchangeably.

[0302] In some embodiments, “get,” “obtain,” “receive,” “transmit,” “bidirectional transmission,” and “send and / or receive” can be used interchangeably and can be interpreted as receiving from other entities, obtaining from protocols, obtaining from higher layers, obtaining through self-processing, or autonomous implementation, among other meanings.

[0303] In some embodiments, terms such as "certain," "preset," "default," "set," "indicated," "a certain," "any," and "first" can be used interchangeably. "Certain A," "preset A," "default A," "set A," "indicated A," "a certain A," "any A," and "first A" can be interpreted as A pre-defined in a protocol or the like, or as A obtained through setting, configuration, or instruction, or as specific A, a certain A, any A, or first A, but are not limited thereto.

[0304] In some embodiments, the communication method involved in this disclosure may include at least one of steps S2101 to S2104. For example, step S2101 may be implemented as a standalone embodiment, step S2102 may be implemented as a standalone embodiment, step S2101+S2102 may be implemented as a standalone embodiment, step S2103 may be implemented as a standalone embodiment, steps S2101 to S2103 may be implemented as standalone embodiments, step S2104 may be implemented as a standalone embodiment, and steps S2101 to S2104 may be implemented as standalone embodiments, but are not limited thereto.

[0305] In some embodiments, steps S2101 to S2104 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0306] In some embodiments, the execution order of steps S2101 to S2104 is not limited.

[0307] In the above embodiments, the complexity of LTM execution on the terminal is reduced and the availability of LTM is improved.

[0308] Figure 3A is a flowchart illustrating a communication method according to an embodiment of the present disclosure. As shown in Figure 3A, the present disclosure relates to a communication method that can be executed by a terminal 101, and the method includes:

[0309] Step S3101: Obtain the first MAC CE.

[0310] In some embodiments, the first MAC CE includes first information, which is key information related to a mobility LTM triggered by layer 1 or layer 2.

[0311] In some embodiments, optional implementations of step S3101 can be found in optional implementations of step S2101 in FIG2 and other related parts in the embodiments involved in FIG2, which will not be repeated here.

[0312] In some embodiments, terminal 101 receives a first MAC CE sent by network device 102, but is not limited thereto. Terminal 101 may also receive a first MAC CE sent by other entities, such as relay devices or other devices, in which case step S3101 may be omitted.

[0313] In some embodiments, terminal 101 obtains the first MAC CE as defined by the protocol, in which case step S3101 is omitted.

[0314] In some embodiments, terminal 101 obtains the first MAC CE from the upper layer(s), in which case step S3101 is omitted.

[0315] In some embodiments, the terminal 101 performs processing to obtain the first MAC CE, in which step S3101 is omitted.

[0316] In some embodiments, the terminal 101 autonomously implements the function indicated by the first MAC CE, or the above function is default or default, in which case step S3101 is omitted.

[0317] Step S3102: Determine whether to perform the first operation.

[0318] In some embodiments, optional implementations of step S3101 can be found in optional implementations of step S2103 in FIG2 and other related parts in the embodiments involved in FIG2, which will not be repeated here.

[0319] In some embodiments, steps S3101 to S3102 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0320] In some embodiments, the execution order of steps S3101 to S3102 is not limited.

[0321] In the above embodiments, the complexity of LTM execution on the terminal is reduced and the availability of LTM is improved.

[0322] Figure 3B is a flowchart illustrating a communication method according to an embodiment of the present disclosure. As shown in Figure 3B, the present disclosure relates to a communication method that can be executed by a network device 102, and the method includes:

[0323] Step S3201: Send the first MAC CE.

[0324] In some embodiments, the first MAC CE includes first information, which is key information related to a mobility LTM triggered by layer 1 or layer 2.

[0325] In some embodiments, network device 102 sends a first MAC CE to terminal 101.

[0326] In some embodiments, terminal 101 receives a first MAC CE.

[0327] In some embodiments, optional implementations of step S3201 can be found in optional implementations of step S2101 in FIG2 and other related parts in the embodiments involved in FIG2, which will not be repeated here.

[0328] In the above embodiments, the network device can provide first information through the first MAC CE, enabling the terminal to determine whether to perform the first operation based on the first information, thereby reducing the complexity of the terminal performing LTM and improving the availability of LTM.

[0329] The above process is further illustrated with examples below.

[0330] In this embodiment of the disclosure, for MCG LTM, the terminal can determine whether to perform key update and / or PDCP reconstruction based on the value of the NCC field contained in the LTM Cell Switch Command MAC CE message sent by the network device. If the NCC field value is 0 (or other specific value, such as 1) or the NCC field value is less than the current NCC value, the UE does not perform key update and PDCP reconstruction; otherwise, it performs key update and corresponding PDCP reconstruction based on this NCC value.

[0331] For SCG LTM, the MN or SN sends an LTM Cell Switch Command MAC CE to the terminal, and indicates the increment or value of the sk-counter in the LTM Cell Switch Command MAC CE; where the increment of the sk-counter refers to the increment of the sk-counter corresponding to the key of the source SN.

[0332] If the increment is 0, it means that key update and PDCP reconstruction are not performed (for SN terminated bearer without change of termination point); otherwise, a new sk-counter is determined based on the increment of sk-counter and SN key update and / or corresponding PDCP reconstruction are performed.

[0333] In the case of SN-initiated inter-SN SCG LTM, the increment of this sk-counter is generated by the MN, which then generates the corresponding SN key and sends it to the target SN. The MN also sends the increment of the sk-counter to the source SN, which then carries it in the LTM Cell Switch Command MAC CE and sends it to the UE. The SN can send a request message to the MN to request a key update before triggering the LTM Cell Switch Command MAC CE, and include the target SN in the request message.

[0334] Example 1, Key update of MCG LTM: determined based on MAC CE message carrying key information.

[0335] In this embodiment, each point, such as x, xy, xyz, and xyzq, can be an independent embodiment or implementation. Here, x, y, z, and q are integers.

[0336] 1. The terminal (hereinafter referred to as "UE") determines whether to perform key update and / or PDCP reconstruction based on the value of the NCC field contained in the MAC CE message sent by the network side. For example, this MAC CE can be the LTM Cell Switch Command MAC CE that triggers LTM, which can carry the key-related information of this LTM Cell Switch, i.e., the NCC field.

[0337] 1.1 If the NCC field value is 0 (or other specific value, such as 1), the UE will not perform key update and PDCP reconstruction during LTM execution; otherwise (the NCC field value is not 0 (or other specific value, such as 1)), the UE will perform key update and / or PDCP reconstruction based on the NCC value indicated in the MAC CE.

[0338] 1.1.1, where the NCC field value of 0 can also be referred to as this field being replaced by R bit, where R bit refers to reserved bit, set to 0.

[0339] 1.1.2 For example, the protocol stipulates that the NCC value for key updates during the inter-CU MCG LTM process cannot be 0 (or other specific values, such as 1), or stipulates that the initial inter-CU MCG LTM (that is, the first inter-CU MCG LTM after the UE receives the RRC reconfiguration message sent by the network side) can only be a vertical key update (not a horizontal key update), or the protocol stipulates that inter-CU MCG LTM only supports vertical key updates.

[0340] 1.2 If the NCC field value is less than the source cell's NCC, the UE will not perform key update and PDCP reconstruction during LTM execution; otherwise (the NCC field value is greater than or equal to the source cell's NCC), the UE will perform key update and / or PDCP reconstruction based on the NCC value indicated in the LTM Cell Switch Command MAC CE.

[0341] 1.2.1, For example, the protocol stipulates that the NCC value during the key update in the inter-CU MCG LTM process is incremented. If the NCC reaches the maximum value, the network side needs to update the AMF key and inform the UE to perform a Key AMF update, and generate a new initial Key_gNB (or Key_NG-RAN, Key_MN) based on the updated key_AMF.

[0342] 1.3 The UE performs a key update based on the NCC value indicated in the MAC CE.

[0343] 1.1.1 The UE determines a new KgNB key based on the current KgNB key or NH and the NCC value indicated in the MAC CE: If the NCC is equal to the NCC corresponding to the current KgNB key, the UE generates a new KgNB key based on the current KgNB key and the NCC; if they are not equal, the UE generates a new KgNB key based on the NCC and the NH corresponding to this NCC.

[0344] 1.4 If the NCC is instructed via LTM Cell Switch Command MAC CE, its MAC CE structure is as shown in Figure 4B.

[0345] 2. The UE determines whether to perform key update and / or PDCP reconstruction based on the indication information contained in the MAC CE sent by the network side.

[0346] 2.1 If the indication information is "true", then key update and / or PDCP reconstruction shall be performed based on the NCC indicated in the MAC CE; otherwise, key update and / or PDCP reconstruction shall not be performed.

[0347] 2.2. Its MAC CE structure is shown in Figure 4A, for example, where field E represents this indication information.

[0348] 3. The UE determines whether to perform key update and / or PDCP reconstruction based on the values ​​of the first ID and NCC fields.

[0349] 3.1, where the first ID is configured by the network side through RRC messages. The network side will configure the corresponding first ID for the serving cell and the candidate cell (the first ID of the serving cell and the first ID of the candidate cell can correspond to different RRC field names).

[0350] 3.2, Example 1: The protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are the same, the LTM Cell Switch Command MAC CE sent by the NW will not carry the NCC field (i.e., this field is replaced by the R field, i.e., the value is 0) or the NCC field value will be set to 0 (or less than the current NCC value); the protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are different, the LTM Cell Switch Command MAC CE sent by the NW needs to carry the NCC field, and further, the value of this NCC field is not 0.

[0351] 3.3, Example 2: If the first ID of the serving cell is the same as the first ID of the candidate cell, but the NCC field value of the LTM Cell Switch Command MAC CE sent by the NW is not 0 (or greater than or equal to the current NCC value), then the UE performs key update and / or PDCP reconstruction.

[0352] 3.4, Example 3: If the first ID of the serving cell and the first ID of the candidate cell are different, but the LTM Cell Switch Command MAC CE sent by the NW does not carry the NCC field (i.e., this field is replaced by the R field, i.e., the value is 0) or the NCC field value is 0 (or less than the current NCC value), then the UE will not execute the LTM Cell Switch Command MAC CE and will send an indication message to the current serving cell to inform it of the key configuration error.

[0353] 4. The NCC field is not included in the LTM Cell Switch Command MAC CE. Before sending the LTM Cell Switch Command MAC CE (or before triggering the LTM Cell Switch Command MAC CE), the NW sends the first MAC CE message carrying key-related information to the UE. The UE stores the received key-related information NCC value.

[0354] 4.1 When the UE receives an LTM Cell Switch Command MAC CE sent by the network side, or when an LTM Cell Switch is triggered due to an event or failure recovery,

[0355] 4.1.1 If the first ID of the serving cell is the same as the first ID of the candidate cell, the UE does not perform key update and / or PDCP reconstruction.

[0356] 4.1.2 If the first ID corresponding to the serving cell and the first ID corresponding to the candidate cell are different, the UE performs key update and / or PDCP reconstruction based on the stored NCC value from the first MAC CE.

[0357] 5. When the UE receives an LTM handover command MAC CE containing NCC sent by the network side, the UE performs key update and / or PDCP reconstruction (corresponding to the first type of first MAC CE).

[0358] 5.1, For example, the UE receives an LTM handover command MAC CE containing NCC sent by the network side, which can be an enhanced LTM Cell Switch Command MAC CE.

[0359] 5.1.1 For example, in the enhanced LTM Cell Switch Command MAC CE, the NCC corresponds to a separate line. In this line, the NCC can be placed in any 3 consecutive bits of the 8 bits in this line, and the other positions are reserved bits.

[0360] 6. When the UE receives an LTM handover command MAC CE sent by the network side that does not contain NCC, the UE does not need to perform key update and / or PDCP reconstruction (corresponding to the second type of first MAC CE).

[0361] 6.1, For example, the UE receives an LTM handover command MAC CE from the network side that does not contain NCC. This MAC CE can be an LTM Cell Switch Command MAC CE. 7. The UE determines whether to perform a key update and / or PDCP reconstruction based on the first ID and the category (whether it contains NCC) of the received LTM handover command MAC CE.

[0362] 7.1, where the first ID is configured by the network side via RRC messages. The network side will configure the corresponding first ID for the serving cell and the candidate cell. (The first ID of the serving cell and the first ID of the candidate cell can correspond to different RRC field names).

[0363] 7.2, Example 1: The protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are the same, the network side can only send the UE an LTM handover command MAC CE (e.g., LTM Cell Switch Command MAC CE) without NCC; the protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are different, the NW can only send the UE an LTM handover command MAC CE with NCC (e.g., Enhanced LTM Cell Switch Command MAC CE).

[0364] 7.3, Example 2: If the first ID of the serving cell is the same as the first ID of the candidate cell, but the NW sends an LTM handover command MAC CE containing NCC to the UE (e.g., Enhanced LTM Cell Switch Command MAC CE), then the UE performs key update and / or PDCP reconstruction.

[0365] 7.4, Example 3: If the first ID of the serving cell and the first ID of the candidate cell are different, but the NW sends the UE an LTM handover command MAC CE that does not contain NCC (e.g., LTM Cell Switch Command MAC CE), then the UE will not execute the LTM Cell Switch Command MAC CE and will send an indication message to the current serving cell to inform it of the key configuration error.

[0366] The key update process of MCG LTM can be illustrated as shown in Figure 4E, and includes the following steps:

[0367] In step S4501, network device 102 sends the first MAC CE to terminal 101.

[0368] In some embodiments, terminal 101 receives a first MAC CE.

[0369] The first MAC CE can be either the first type of first MAC CE or the second type of first MAC CE mentioned above, and this disclosure does not limit it.

[0370] Step S4502, terminal 101 stores the first information.

[0371] In some embodiments, the NCC field is not included in the LTM Cell Switch Command MAC CE. Before sending the LTM Cell Switch Command MAC CE (or before triggering the LTM Cell Switch Command MAC CE), the NW sends a first MAC CE message carrying key-related information to the UE. The terminal 101 can store the received key-related information NCC value.

[0372] Furthermore, based on the first identifier, it can be determined whether to perform key update and / or PDCP reconstruction operations, such as point 4 in the aforementioned embodiment 1.

[0373] In step S4503, terminal 101 determines whether to perform the first operation. In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction operations based on the value of the first field included in the first MAC CE, such as point 1 in the aforementioned embodiment 1.

[0374] In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction operations based on indication information included in the first MAC CE, such as point 2 in the aforementioned embodiment 1.

[0375] In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction operations based on the value of the first identifier and the first field included in the first MAC CE, such as point 3 in the aforementioned embodiment 1.

[0376] In step S4504, terminal 101 determines whether to perform key update and / or PDCP reconstruction operations based on the first ID and the category (whether it includes NCC) of the received LTM switching command MAC CE.

[0377] In some embodiments, this implementation process is, for example, point 7 in the aforementioned embodiment 1. Steps S4503 and S4504 may be performed selectively.

[0378] In step S4505, terminal 101 performs key update and / or PDCP reconstruction operations, or does not perform key update and / or PDCP reconstruction operations.

[0379] In one example, if the first MAC CE is the first type of first MAC CE mentioned above, then the terminal 101 can perform key update and / or PDCP reconstruction when it receives the LTM handover command MAC CE containing NCC sent by the network device 102, for example, point 5 in the aforementioned embodiment 1.

[0380] In one example, if the first MAC CE is the second type of first MAC CE mentioned above, then the terminal 101 may not perform key update and / or PDCP reconstruction when it receives the LTM handover command MAC CE without NCC sent by the network device 102, for example, point 6 in the aforementioned embodiment 1.

[0381] In some embodiments, steps S4501 to S4505 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0382] In some embodiments, the execution order of steps S4501 to S4505 is not limited.

[0383] In the above embodiments, the complexity of the terminal executing MCG LTM is reduced and the availability of LTM is improved.

[0384] Example 2, SCG LTM key update: Clarify how to carry SCG LTM key information through MAC CE, and determine whether to perform key update and PDCP reconstruction of SN terminated bearer based on key information.

[0385] In this embodiment, each point, such as x, xy, xyz, and xyzq, can be an independent embodiment or implementation. Here, x, y, z, and q are integers.

[0386] 1. The NW (MN or SN) sends a MAC CE to the UE and indicates SN key-related information in the MAC CE. For example, this MAC CE can be the LTM Cell Switch Command MAC CE that triggers LTM.

[0387] 1.1, Example 1, The LTM Cell Switch Command MAC CE contains the value of the sk-counter corresponding to the target candidate PSCell.

[0388] 1.2, Example 2, Including the increment of the sk-counter corresponding to the target candidate PSCell in the LTM Cell Switch Command MAC CE.

[0389] 1.2.1, where the increment of sk-counter refers to the increment of sk-counter compared to the key of the source SN (i.e. the key of the current SN).

[0390] 2. The UE determines whether to perform key update and / or PDCP reconstruction based on the value of the SN key information (sk-counter or sk-counter increment) field contained in the MAC CE message sent by the network side (similar to the method in MCG LTM of determining whether to perform key update and / or PDCP reconstruction based on the NCC value).

[0391] 2.1 If the SN key information field is 0 (or this field is replaced by Rbit), the UE does not perform key update and PDCP reconstruction during LTM execution. Otherwise, the SN key and PDCP reconstruction corresponding to the target candidate cell are determined based on the SN key information and the MN key (for SN terminated bearer without change of termination point).

[0392] For example, if the increment is 0, it means that no key update and PDCP reconstruction are performed (for SN terminated bearer without change of termination point); otherwise, a new sk-counter is determined based on the increment of the sk-counter and the SN key update and corresponding PDCP reconstruction are performed.

[0393] 2.2 The UE determines whether to perform key update and / or PDCP reconstruction based on the indication information contained in the MAC CE sent by the network side.

[0394] 2.2.1 If the indication information is "true", then the SN key information indicated in the MAC CE is updated and / or the PDCP is reconstructed; otherwise, the key update and / or PDCP reconstruction is not performed.

[0395] 2.3 The UE determines whether to perform key update and / or PDCP reconstruction based on the values ​​of the first ID and SN key information fields. The first ID is configured by the network side through RRC messages. The network side will configure the corresponding first ID for the serving cell and the candidate cell (the first ID of the serving cell and the first ID of the candidate cell can correspond to different RRC field names).

[0396] 2.3.1, Example 1: The protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are the same, the LTM Cell Switch Command MAC CE sent by the NW will not carry the SN key information field (i.e., this field is replaced by the R field, i.e., the value is 0) or the SN key information field will be set to 0; the protocol stipulates that if the first ID of the serving cell and the first ID of the candidate cell are different, the LTM Cell Switch Command MAC CE sent by the NW needs to carry the SN key information field, and further, the value of this SN key information field is not 0 (if this SN key information corresponds to the increment of the sk-counter, this value can be 1, or other values ​​greater than 1).

[0397] 2.3.2, Example 2: If the first ID of the serving cell is the same as the first ID of the candidate cell, but the SN key information field of the LTM Cell Switch Command MAC CE sent by the NW is not 0, then the UE performs key update and / or PDCP reconstruction.

[0398] 2.3.3, Example 3: If the first ID of the serving cell and the first ID of the candidate cell are different, but the LTM Cell Switch Command MAC CE sent by the NW does not carry the SN key information field (i.e., this field is replaced by the R field, i.e., the value is 0) or the SN key information field is 0, then the UE will not execute the LTM Cell Switch Command MAC CE, and will send an indication message to the current serving cell to inform it of the key configuration error.

[0399] 3. The SN key information field is not included in the LTM Cell Switch Command MAC CE. Before sending the LTM Cell Switch Command MAC CE (or before triggering the LTM Cell Switch Command MAC CE), the NW sends the first MAC CE message carrying the SN key information field to the UE. The UE stores the value of the received SN key information (sk-counter or the increment of sk-counter).

[0400] 3.1. When the UE receives an LTM Cell Switch Command MAC CE sent by the network side or triggers an SCG LTM Cell Switch based on an event,

[0401] 3.1.1 If the first ID corresponding to the serving cell PSCell is the same as the first ID corresponding to the candidate cell PSCell, the UE does not perform key update and / or PDCP reconstruction.

[0402] 3.1.2 If the first ID corresponding to the serving cell PSCell is different from the first ID corresponding to the candidate cell PSCell, the UE performs key update and / or PDCP reconstruction based on the value of the stored SN key information from the first MAC CE.

[0403] 4. Between MN and SN.

[0404] For SN-initiated inter-SN SCG LTM (i.e., the LTM Cell Switch Command MAC CE sent by the SN to the UE contains SN key-related information), this SN key-related information (the value of sk-counter or the increment of sk-counter) is generated by MN.

[0405] 4.1 For points 1-2 of Example 2, the MN generates the corresponding SN key and sends it to the target SN, and sends the SN key related information (the value of sk-counter or the increment of sk-counter) to the source SN, which then carries it in the LTM Cell Switch Command MAC CE and sends it to the UE.

[0406] 4.1.1 The source SN can send a request message to the MN to request a key update before triggering SCG LTM (such as inter-SN SCG LTM), i.e., before sending the LTM Cell Switch Command MAC CE to the UE. Optionally, the target SN can be included in the request message. Then, after receiving this request message, the MN sends SN key-related information (the value of sk-counter or the increment of sk-counter) to the source SN. The source SN includes this SN key-related information in the LTM Cell Switch Command MAC CE and sends it to the UE.

[0407] 4.2 Regarding point 3 of embodiment 2, the MN sends the SN key information for the next inter-SN SCG LTM to the UE through the first MAC CE message.

[0408] The key update process of SCG LTM can be illustrated as shown in Figure 4F, and includes the following steps:

[0409] Step S4601, the interaction between MN and SN.

[0410] In one example, for SN initiated inter-SN SCG LTM (i.e., the LTM Cell Switch Command MAC CE sent by the SN to the UE contains SN key-related information), this SN key-related information (the value of sk-counter or the increment of sk-counter) is generated by MN, such as point 4 in the aforementioned embodiment 2.

[0411] For points 1-2 of Embodiment 2, in step S4601a, the MN generates the corresponding SN key and sends it to the target SN. In step S4601b, the MN sends the SN key related information (the value of sk-counter or the increment of sk-counter) to the source SN, which then carries it in the LTM Cell Switch Command MAC CE and sends it to the UE.

[0412] Regarding point 3 of embodiment 2, the MN subsequently sends the SN key information for the next inter-SN SCG LTM to the UE through the first MAC CE message. At this time, only step S4601a needs to be executed.

[0413] In step S4602, network device 102 sends the first MAC CE to terminal 101.

[0414] In some embodiments, terminal 101 receives a first MAC CE, such as point 1 in the aforementioned embodiment 2.

[0415] In some embodiments, for SCG LTM, if the aforementioned steps S4601a and S4601b are executed, then step S4601a is executed, in which the source SN sends a first MAC CE to the terminal 101. If the aforementioned step S4601a is executed, then step S4601b is executed, in which the MN sends a first MAC CE to the terminal 101.

[0416] The first MAC CE can be either the first type of first MAC CE or the second type of first MAC CE mentioned above, and this disclosure does not limit it.

[0417] Step S4603: Terminal 101 stores the first information.

[0418] In some embodiments, the SN key information field is not included in the LTM Cell Switch Command MAC CE. Before sending the LTM Cell Switch Command MAC CE (or before triggering the LTM Cell Switch Command MAC CE), the NW sends a first MAC CE message carrying the SN key information field to the UE, and the UE stores the value of the received SN key information (sk-counter or the increment of sk-counter).

[0419] Furthermore, based on the first identifier, it can be determined whether to perform key update and / or PDCP reconstruction operations, such as point 3 in the aforementioned embodiment 2.

[0420] In step S4604, terminal 101 determines whether to perform the first operation.

[0421] In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction based on the value of the SN key information (sk-counter or sk-counter increment) field included in the first MAC CE, such as point 2.1 in the aforementioned embodiment 2.

[0422] In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction operations based on indication information included in the first MAC CE, such as point 2.2 in the aforementioned embodiment 2.

[0423] In some embodiments, terminal 101 may determine whether to perform key update and / or PDCP reconstruction operations based on the first identifier and the value of the SN key information field in the first MAC CE, such as point 2.3 in the aforementioned embodiment 2.

[0424] In step S4605, terminal 101 performs key update and / or PDCP reconstruction operations, or does not perform key update and / or PDCP reconstruction operations.

[0425] In some embodiments, this step is implemented in a similar manner to the aforementioned step S4505, and will not be described again here.

[0426] In some embodiments, steps S4601 to S4605 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0427] In some embodiments, the execution order of steps S4601 to S4605 is not limited.

[0428] In the above embodiments, the complexity of the terminal executing SCG LTM is reduced and the availability of LTM is improved.

[0429] This disclosure also proposes an apparatus (also referred to as a communication device, etc.) for implementing any of the above methods. For example, an apparatus is proposed that includes units or modules for implementing the steps performed by the terminal in any of the above methods. Furthermore, another apparatus is proposed that includes units or modules for implementing the steps performed by a network device (e.g., an access network device, a core network functional node, a core network device, etc.) in any of the above methods.

[0430] It should be understood that the division of units or modules in the above device is only a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, the units or modules in the device can be implemented by a processor calling software: for example, the device includes a processor connected to a memory containing instructions. The processor calls the instructions stored in the memory to implement any of the above methods or to implement the functions of the units or modules in the above device. The processor can be, for example, a general-purpose processor, such as a Central Processing Unit (CPU) or a microprocessor, and the memory can be internal or external to the device. Alternatively, the units or modules in the device can be implemented in the form of hardware circuits. The functionality of some or all of the units or modules can be achieved through the design of these hardware circuits, which can be understood as one or more processors. For example, in one implementation, the hardware circuit is an application-specific integrated circuit (ASIC). The functionality of some or all of the units or modules is achieved through the design of the logical relationships between the components within the circuit. In another implementation, the hardware circuit can be implemented using a programmable logic device (PLD). Taking a field-programmable gate array (FPGA) as an example, it can include a large number of logic gates. The connection relationships between the logic gates are configured through configuration files, thereby achieving the functionality of some or all of the units or modules. All units or modules of the above device can be implemented entirely through processor-called software, entirely through hardware circuits, or partially through processor-called software with the remaining parts implemented through hardware circuits.

[0431] In this embodiment, the processor is a circuit with signal processing capabilities. In one implementation, the processor can be a circuit with instruction read and execute capabilities, such as a Central Processing Unit (CPU), a microprocessor, a graphics processing unit (GPU) (which can be understood as a microprocessor), or a digital signal processor (DSP). In another implementation, the processor can implement certain functions through the logical relationships of hardware circuits. The logical relationships of the aforementioned hardware circuits are fixed or reconfigurable. For example, the processor is a hardware circuit implemented using an application-specific integrated circuit (ASIC) or a programmable logic device (PLD), such as an FPGA. In a reconfigurable hardware circuit, the process of the processor loading a configuration document and configuring the hardware circuit can be understood as the process of the processor loading instructions to implement the functions of some or all of the above units or modules. Furthermore, it can also be a hardware circuit designed for artificial intelligence, which can be understood as an ASIC, such as a Neural Network Processing Unit (NPU), a Tensor Processing Unit (TPU), or a Deep Learning Processing Unit (DPU).

[0432] Figure 5A is a schematic diagram of the structure of a terminal according to an embodiment of this disclosure. The terminal 5100 is used to execute any of the above methods. In some embodiments, as shown in Figure 5A, the terminal 5100 may include at least one of a transceiver module 5101 and a processing module 5102.

[0433] In some embodiments, the transceiver module 5101 is used to receive a first media access control unit (MAC CE) sent by a network device.

[0434] In some embodiments, the processing module 5102 is used to determine whether to perform a first operation based on the first information included in the first MAC CE; or to determine whether to perform a first operation based on whether the first information is included in the first MAC CE; wherein the first information is key information related to triggering mobility LTM at layer 1 or layer 2, and the first operation includes a key update operation and / or a packet data convergence protocol (PDCP) reconstruction operation.

[0435] Optionally, the transceiver module 5101 is used to perform at least one of the communication steps (such as step S2101, step S2102, but not limited thereto) performed by the terminal 5100 in any of the above methods, which will not be described in detail here.

[0436] Optionally, the processing module 5102 is used to execute at least one of the other steps (such as step S2103, step S2104, but not limited thereto) executed by the terminal 5100 in any of the above methods, which will not be described in detail here.

[0437] Figure 5B is a schematic diagram of the structure of a network device according to an embodiment of this disclosure. The network device 5200 is used to perform any of the above methods. In some embodiments, as shown in Figure 5B, the network device 5200 may include a transceiver module 5201.

[0438] In some embodiments, the transceiver module 5201 is used to send a first media access control unit (MAC CE) to a terminal; wherein, the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or, whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information is key information related to triggering mobility LTM at layer 1 or layer 2, and the first operation includes a key update operation and / or a packet data convergence protocol (PDCP) reconstruction operation.

[0439] Optionally, the transceiver module 5201 is used to perform at least one of the communication steps (such as step S2101, step S2102, but not limited thereto) performed by the network device 5200 in any of the above methods, which will not be described in detail here.

[0440] In some embodiments, the transceiver module may include a transmitting module and / or a receiving module, which may be separate or integrated. Optionally, the transceiver module may be interchangeable with a transceiver.

[0441] In some embodiments, the processing module may be a single module or may include multiple sub-modules. Optionally, the multiple sub-modules may each perform all or part of the steps required by the processing module. Optionally, the processing module may be interchangeable with a processor, and the transceiver module may be interchangeable with a transceiver.

[0442] Figure 6A is a schematic diagram of the structure of the communication device 6100 proposed in an embodiment of this disclosure. The communication device 6100 can be a network device (e.g., access network device, core network device, etc.), a terminal (e.g., user equipment, etc.), a chip, chip system, or processor that supports the network device in implementing any of the above methods, or a chip, chip system, or processor that supports the terminal in implementing any of the above methods. The communication device 6100 can be used to implement the methods described in the above method embodiments; for details, please refer to the descriptions in the above method embodiments.

[0443] As shown in Figure 6A, the communication device 6100 is used to execute any of the above methods. In some embodiments, the communication device 6100 includes one or more processors 6101. The processor 6101 may be a general-purpose processor or a special-purpose processor, such as a baseband processor or a central processing unit. The baseband processor may be used to process communication protocols and communication data, and the central processing unit may be used to control communication devices (e.g., base stations, baseband chips, terminal devices, terminal device chips, DUs or CUs, etc.), execute programs, and process program data. Optionally, the communication device 6100 is used to execute any of the above methods. Optionally, one or more processors 6101 are used to invoke instructions to cause the communication device 6100 to execute any of the above methods.

[0444] In some embodiments, the communication device 6100 further includes one or more transceivers 6102. When the communication device 6100 includes one or more transceivers 6102, the transceiver 6102 performs at least one of the communication steps such as sending and / or receiving in the above method (e.g., steps S2101, S2102, but not limited thereto), and the processor 6101 performs at least one of other steps (e.g., steps S2103, S2104, but not limited thereto). In optional embodiments, the transceiver may include a receiver and / or a transmitter, which may be separate or integrated together. Optionally, the terms transceiver, transceiver unit, transceiver, transceiver circuit, interface circuit, interface, etc., can be used interchangeably; the terms transmitter, transmitting unit, transmitter, transmitting circuit, etc., can be used interchangeably; the terms receiver, receiving unit, receiver, receiving circuit, etc., can be used interchangeably.

[0445] In some embodiments, the communication device 6100 further includes one or more memories 6103 for storing data and / or instructions. Optionally, one or more processors 6101 are used to invoke instructions stored in the memory 6103 to cause the communication device 6100 to perform any of the above methods. Optionally, all or part of the memory 6103 may also be located outside the communication device 6100. In an optional embodiment, the communication device 6100 may include one or more interface circuits 6104. Optionally, the interface circuit 6104 is connected to the memory 6103 and can be used to receive data and / or instructions from the memory 6103 or other devices, and can be used to send data and / or instructions to the memory 6103 or other devices. For example, the interface circuit 6104 can read data and / or instructions stored in the memory 6103 and send the data and / or instructions to the processor 6101.

[0446] The communication device 6100 described in the above embodiments may be a network device or a terminal, but the scope of the communication device 6100 described in this disclosure is not limited thereto, and the structure of the communication device 6100 may not be limited by FIG. 6A. The communication device may be a standalone device or a part of a larger device. For example, the communication device may be: (1) a standalone integrated circuit IC, or chip, or chip system or subsystem; (2) a collection of one or more ICs, optionally, the IC collection may also include storage components for storing data, programs and / or instructions; (3) an ASIC, such as a modem; (4) a module that can be embedded in other devices; (5) a receiver, terminal device, smart terminal device, cellular phone, wireless device, handheld device, mobile unit, vehicle device, network device, cloud device, artificial intelligence device, etc.; (6) others, etc.

[0447] Figure 6B is a schematic diagram of the structure of chip 6200 according to an embodiment of this disclosure. For cases where the communication device 6100 can be a chip or a chip system, please refer to the schematic diagram of chip 6200 shown in Figure 6B, but it is not limited thereto.

[0448] Chip 6200 includes one or more processors 6201. Chip 6200 is used to perform any of the methods described above.

[0449] In some embodiments, chip 6200 further includes one or more interface circuits 6202. Optionally, terms such as interface circuit, interface, and transceiver pin can be used interchangeably. In some embodiments, chip 6200 further includes one or more memories 6203 for storing data and / or instructions. Optionally, all or part of the memories 6203 may be located outside of chip 6200. Optionally, interface circuit 6202 is connected to memory 6203, and interface circuit 6202 can be used to receive data and / or instructions from memory 6203 or other devices, and interface circuit 6202 can be used to send data and / or instructions to memory 6203 or other devices. For example, interface circuit 6202 can read data and / or instructions stored in memory 6203 and send the data and / or instructions to processor 6201.

[0450] In some embodiments, the interface circuit 6202 performs at least one of the communication steps (e.g., steps S2101, S2102, but not limited thereto) in the above-described method, such as sending and / or receiving. For example, the interface circuit 6202 performing the communication steps (e.g., sending and / or receiving) in the above-described method means that the interface circuit 6202 performs data and / or instruction interaction between the processor 6201, the chip 6200, the memory 6203, or the transceiver device. In some embodiments, the processor 6201 performs at least one of other steps (e.g., steps S2103, S2104, but not limited thereto).

[0451] The modules and / or devices described in the various embodiments, such as virtual devices, physical devices, and chips, can be combined or separated arbitrarily as needed. Optionally, some or all steps can also be performed collaboratively by multiple modules and / or devices, which is not limited here.

[0452] This disclosure also proposes a storage medium storing instructions that, when executed on a communication device, cause the communication device to perform any of the above methods. Optionally, the storage medium is an electronic storage medium. Optionally, the storage medium is a computer-readable storage medium, but not limited thereto; it may also be a storage medium readable by other devices. Optionally, the storage medium may be a non-transitory storage medium, but not limited thereto; it may also be a temporary storage medium.

[0453] This disclosure also proposes a program product, including a program and / or instructions, which, when executed by a communication device, cause the communication device to perform any of the above methods. Optionally, the program product is a computer program product. Optionally, the program product is stored on the storage medium.

[0454] This disclosure also proposes a computer program that, when run on a computer, causes the computer to perform any of the above methods.

[0455] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A communication method characterized by comprising: The method is executed by a terminal, and the method includes: Receives the first Media Access Control Unit (MAC) CE sent by the network device; Based on the first information included in the first MAC CE, determine whether to perform the first operation; or Based on whether the first MAC CE includes the first information, determine whether to perform the first operation; The first information is key information related to triggering LTM mobility at layer 1 or layer 2, and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

2. The method of claim 1, wherein, The first information includes any one of the following: Instruction information, the instruction information being used to indicate whether to perform the first operation; The first field can take any of the following values: Next-hop chained counter NCC field; Based on the initial configuration of the secondary node's security counter sk-counter field; Reserved fields.

3. The method of claim 2, wherein, The sk-counter field is used to indicate any of the following: The values ​​of sk-counter corresponding to the target primary and secondary cells and / or candidate primary and secondary cells; The values ​​of sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node; The change in the value of the sk-counter corresponding to the target primary and secondary cells and / or candidate primary and secondary cells relative to the value of the sk-counter of the source primary and secondary cells; The change in the value of the sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node relative to the value of the sk-counter of the source auxiliary node.

4. The method according to claim 2 or 3, characterized in that, The determination of whether to perform the first operation based on the first information included in the first MAC CE includes at least one of the following: Based on the value of the first field, determine whether to execute the first operation; Based on the indicated information, determine whether to perform the first operation; Based on the value of the first identifier and the first field, it is determined whether to perform the first operation, wherein the first identifier is used to identify the access network device.

5. The method of claim 4, wherein, Determining whether to perform the first operation based on the value of the first field includes any one of the following: If the value of the first field is the first value, then the first operation will not be performed. If the value of the first field is the second value, then the first operation is executed. If the value of the first field is less than the NCC value corresponding to the source cell, it is determined that the first operation will not be performed; If the value of the first field is greater than or equal to the NCC value corresponding to the source cell, then the first operation is executed.

6. The method of claim 5, wherein, The method further includes at least one of the following: Based on the agreement, when performing LTM between centralized units (CUs), the value of the first field cannot be the first value. Based on the agreement, when performing LTM between CUs, the value of the first field needs to be updated; Based on the protocol agreement, vertical key updates are supported when performing LTM between CUs.

7. The method according to any one of claims 3-6, characterized in that, The value of the first field is incrementing; and / or If the value of the first field reaches its maximum value, it will start incrementing again from the initial value.

8. The method according to any one of claims 3-7, characterized in that, The method further includes at least one of the following: If the first operation is not performed based on the first identifier, it is determined that the NCC field is not included in the first MAC CE; If the first operation is not performed based on the first identifier, it is determined that the sk-counter field is not included in the first MAC CE; If it is determined that the first operation will not be performed based on the first identifier, it is determined that the first MAC CE includes the reserved field, and the value of the reserved field is a first value; If it is determined that the first operation will not be performed based on the first identifier, it is determined that the first MAC CE includes the NCC field, and the value of the NCC field is a first value; If it is determined that the first operation will not be performed based on the first identifier, it is determined that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a first value; When the first operation is determined to be performed based on the first identifier, it is determined that the first MAC CE includes the NCC field, and the value of the NCC field is a second value; When the first operation is determined to be performed based on the first identifier, it is determined that the first MAC CE includes the sk-counter field, and the value of the sk-counter field is a second value.

9. The method according to any one of claims 4-8, characterized in that, Determining whether to perform the first operation based on the first identifier and the value of the first field includes any one of the following: If it is determined that the first operation will not be performed based on the first identifier, and it is determined that the first operation will not be performed based on the value of the first field, then it is determined that the first operation will not be performed. If the execution of the first operation is determined based on the first identifier, and the execution of the first operation is determined based on the value of the first field, then the execution of the first operation is determined. If it is determined not to perform the first operation based on the first identifier, but determined to perform the first operation based on the value of the first field, then the first operation is to be performed. If the first operation is determined to be executed based on the first identifier, but not based on the value of the first field, then the first operation is determined not to be executed.

10. The method of claim 9, wherein, The method further includes: If the first operation is determined to be executed based on the first identifier, but not based on the value of the first field, a notification message is sent to the network device. The notification message is used to notify the network device of a key configuration error.

11. The method according to any one of claims 8-10, characterized in that, The method further includes any one of the following: If the first identifier of the serving cell and the first identifier of the candidate cell are different, the first operation will be performed. If the first identifier of the serving cell is different from the first identifier of the candidate configuration, then the first operation will be performed. If the first identifier of the serving cell and the first identifier of the candidate cell are the same, it is determined that the first operation will not be performed. If the first identifier of the serving cell is the same as the first identifier of the candidate configuration, it is determined that the first operation will not be performed.

12. The method according to any one of claims 1 to 11, characterized in that, The step of determining whether to perform the first operation based on whether the first information is included in the first MAC CE includes any one of the following: If the first information is included in the first MAC CE, it is determined that the first operation will be performed; If the first information is not included in the first MAC CE, it is determined that the first operation will not be performed.

13. The method according to any one of claims 1 to 12, characterized in that, The first MAC CE is also used to trigger the terminal to perform LTM cell handover.

14. The method according to any one of claims 1 to 12, characterized in that, The method further includes: Store the first information; The step of determining whether to perform the first operation based on the first information includes: Upon receiving a second MAC CE sent by the network device or upon triggering an LTM cell handover based on an event, the system determines whether to execute the first operation based on the stored first information. The second MAC CE is used to trigger the terminal to perform an LTM cell handover.

15. The method according to any one of claims 1-14, characterized in that, In the case where a secondary cell group LTM between SNs is triggered by a secondary node SN, the network device includes any of the following: Source SN, wherein the source SN obtains the first information from the master node MN; MN.

16. A method of communication, comprising: The method is performed by a network device, and the method includes: Send a first Media Access Control Unit (MAC CE) to the terminal; wherein, the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or, whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information is key information related to Layer 1 or Layer 2 Triggered Mobility LTM, and the first operation includes a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

17. The method of claim 16, wherein, The first information includes any one of the following: Instruction information, the instruction information being used to indicate whether to perform the first operation; The first field can take any of the following values: Next-hop chained counter NCC field; Based on the initial configuration of the secondary node's security counter sk-counter field; Reserved fields.

18. The method of claim 17, wherein, The sk-counter field is used to indicate any of the following: The values ​​of sk-counter corresponding to the target primary and secondary cells and / or candidate primary and secondary cells; The values ​​of sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node; The change in the value of the sk-counter corresponding to the target primary and secondary cells and / or candidate primary and secondary cells relative to the value of the sk-counter of the source primary and secondary cells; The change in the value of the sk-counter corresponding to the target auxiliary node and / or candidate auxiliary node relative to the value of the sk-counter of the source auxiliary node.

19. The method of claim 17 or 18, wherein, The method further includes at least one of the following: Based on the agreement, when performing LTM between centralized units (CUs), the value of the first field cannot be the first value. Based on the agreement, when performing LTM between CUs, the value of the first field needs to be updated; Based on the protocol agreement, vertical key updates are supported when performing LTM between CUs.

20. The method according to any one of claims 17-19, characterized by, The value of the first field is incrementing; and / or If the value of the first field reaches its maximum value, it will start incrementing again from the initial value.

21. The method according to any one of claims 16-20, characterized by, The method further includes: The system receives a notification message sent by the terminal when it determines to perform the first operation based on a first identifier, but determines not to perform the first operation based on the value of the first field. The first identifier is used to identify the access network device, and the notification message is used to notify the network device of a key configuration error.

22. The method according to any one of claims 16-21, characterized by, The first MAC CE is also used to trigger the terminal to perform LTM cell handover.

23. The method according to any one of claims 16-22, characterized by, The method further includes: A second MAC CE is sent to the terminal, which is used to trigger the terminal to perform LTM cell handover.

24. The method according to any one of claims 16-23, characterized in that, In the case where a secondary cell group LTM between SNs is triggered by a secondary node SN, the network device includes any of the following: Source SN, wherein the source SN obtains the first information from the master node MN; MN.

25. The method of claim 24, wherein, The method further includes: When the network device includes the source SN, it sends a request message to the MN. The request message is used to request the updated key and includes the identifier of the target SN. Receive the first information sent by the MN based on the request message.

26. The method of claim 24, wherein, The method further includes: If the network device includes the MN, the generated SN key is sent to the target SN.

27. A terminal, characterized by include: The transceiver module is configured to receive the first media access control unit (MAC CE) sent by the network device; The processing module is configured to determine whether to perform a first operation based on the first information included in the first MAC CE; or to determine whether to perform a first operation based on whether the first MAC CE includes the first information; wherein the first information is key information related to triggering mobility LTM at layer 1 or layer 2, and the first operation includes a key update operation and / or a packet data convergence protocol (PDCP) reconstruction operation.

28. A network device, comprising: include: The transceiver module is configured to send a first media access control unit (MAC CE) to a terminal; wherein the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, or whether the first information included in the first MAC CE is used by the terminal to determine whether to perform a first operation, the first information being key information related to Layer 1 / Layer 2 triggering mobility LTM, and the first operation including a key update operation and / or a Packet Data Convergence Protocol (PDCP) reconstruction operation.

29. A terminal, characterized by include: One or more processors; wherein the processors are configured to perform the method of any one of claims 1-15.

30. A network device, comprising: include: One or more processors; wherein the processors are configured to perform the communication method according to any one of claims 16-26.

31. A communication system, characterized by include: A terminal configured to implement the communication method according to any one of claims 1-15; A network device configured to implement the communication method according to any one of claims 16-26.

32. A storage medium, the storage medium storing instructions, wherein, When the instruction is executed on the communication device, the communication device performs the communication method as described in any one of claims 1-15 or 16-26.

33. A computer program product comprising a computer program, characterized in that, When executed by a processor, the computer program is used to implement the communication method according to any one of claims 1-15 or 16-26.

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