Communication methods and apparatuses, communication device, communication system and storage medium

Abstract

The present disclosure relates to communication methods and apparatuses, a communication device, a communication system, and a storage medium. A method is executed by a terminal. The method comprises: receiving a first message sent by a first network element, wherein the first message carries first information, and the first information is used for configuring an NCC for the terminal. The solution of the present disclosure can achieve key update synchronization in an LTM process.

Description

Communication methods and apparatus, equipment, communication systems and storage media Technical Field

[0001] This disclosure relates to the field of wireless communication, and more particularly to a communication method, apparatus, device, communication system, and storage medium. Background Technology

[0002] In communication systems, handover (HO) is often required during terminal roaming.

[0003] Summary of the Invention

[0004] This disclosure relates to the field of wireless communication, and more particularly to a communication method and apparatus, communication equipment, communication system, storage medium, and program product.

[0005] According to a first aspect of the present disclosure, a communication method is provided. The method is executed by a terminal. The method includes: receiving a first message sent by a first network element, wherein the first message carries first information, the first information being used to configure a next-hop chaining counter (NCC) for the terminal.

[0006] According to a second aspect of the present disclosure, a communication method is provided. The method is performed by a core network device. The method includes: sending a first message to a terminal, wherein the first message carries first information, the first information being used to configure an NCC (Network Control Center) for the terminal.

[0007] According to a third aspect of the present disclosure, a communication method is provided. The method is performed by an access network device. The method includes: sending a first message to a terminal, wherein the first message carries first information, the first information being used to configure an NCC (Neural Control Class Control) for the terminal.

[0008] According to a fourth aspect of the present disclosure, a communication device is provided. The device is disposed in a terminal. The device includes a transceiver module. The transceiver module is configured to: receive a first message sent by a first network element, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0009] According to a fifth aspect of the present disclosure, a communication apparatus is provided. The apparatus is disposed in a core network device. The apparatus includes a transceiver module. The transceiver module is configured to send a first message to a terminal, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0010] According to a sixth aspect of the present disclosure, a communication apparatus is provided. The apparatus is disposed in an access network device. The apparatus includes a transceiver module. The transceiver module is configured to send a first message to a terminal, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0011] According to a seventh aspect of the present disclosure, a communication device is provided. The communication device includes: one or more processors; and a memory storing instructions. When executed by the communication device, the instructions cause the communication device to implement the communication method as described in any one of the first, second, and third aspects.

[0012] According to an eighth aspect of the present disclosure, a communication system is provided. The communication system includes at least one of the following: a terminal, a core network device, and an access network device. The terminal is used to implement the communication method as described in the first aspect. The core network device is used to implement the communication method as described in the second aspect. The access network device is used to implement the communication method as described in the third aspect.

[0013] According to a ninth aspect of the present disclosure, a storage medium is provided. The storage medium stores instructions. When executed on a communication device, the instructions cause the communication device to perform the communication method as described in any one of the first, second, and third aspects.

[0014] According to a tenth aspect of the present disclosure, a program product is provided. When executed by a communication device, the program product causes the communication device to perform the communication method as described in any one of the first, second, and third aspects.

[0015] According to an eleventh aspect of the present disclosure, a computer program is provided. When the computer program is run on a computer, it causes the computer to perform the communication method as described in any one of the first, second, and third aspects.

[0016] According to a twelfth aspect of the present disclosure, a chip or chip system is provided. The chip or chip system includes processing circuitry. The processing circuitry is configured to perform the communication method as described in any one of the first, second, and third aspects.

[0017] According to embodiments of this disclosure, NCC synchronization between the terminal and the network side can be achieved.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not constitute a limitation on the embodiments of this disclosure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments of the invention.

[0020] Figure 1 is a schematic diagram of the architecture of a communication system provided according to an embodiment of the present disclosure.

[0021] Figure 2 shows a schematic diagram of key derivation.

[0022] Figure 3A is an interactive schematic diagram of the communication method provided according to an embodiment of the present disclosure.

[0023] Figure 3B is an interactive schematic diagram of the communication method provided according to an embodiment of the present disclosure.

[0024] Figure 4 is a flowchart illustrating the communication method provided according to an embodiment of the present disclosure.

[0025] Figure 5 is a flowchart illustrating the communication method provided according to an embodiment of the present disclosure.

[0026] Figure 6A is a flowchart illustrating a communication method provided according to an embodiment of the present disclosure.

[0027] Figure 6B is a flowchart illustrating a communication method provided according to an embodiment of the present disclosure.

[0028] Figure 7 is an interactive schematic diagram of the communication method provided according to an embodiment of the present disclosure.

[0029] Figure 8A is an interactive schematic diagram of an exemplary implementation of the communication method provided according to embodiments of the present disclosure.

[0030] Figure 8B is an interactive schematic diagram of an exemplary implementation of the communication method provided according to embodiments of the present disclosure.

[0031] Figure 9 is a schematic diagram of the structure of a communication device provided according to an embodiment of the present disclosure.

[0032] Figure 10A is a schematic diagram of the structure of a communication device provided according to an embodiment of the present disclosure.

[0033] Figure 10B is a schematic diagram of the structure of a chip provided according to an embodiment of the present disclosure. Detailed Implementation

[0034] This disclosure provides a communication method and apparatus, a communication device, a communication system, a storage medium, and a program product.

[0035] In a first aspect, embodiments of this disclosure provide a communication method. The method is executed by a terminal. The method includes: receiving a first message sent by a first network element, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0036] According to this embodiment, the terminal receives a first message sent by a first network element. The first information carried in the first message can be used to configure the NCC for the terminal. In this way, the terminal can obtain an updated NCC, thereby ensuring the implementation of terminal handover.

[0037] In conjunction with some embodiments of the first aspect, in some embodiments, the NCC can be used to implement layer 1 / layer 2 triggered mobility (LTM) handover of the terminal.

[0038] In conjunction with some embodiments of the first aspect, in some embodiments, the first network element may include at least one of the following: core network equipment; access network equipment.

[0039] In conjunction with some embodiments of the first aspect, in some embodiments, the first message may include at least one of the following: a non-access stratum (NAS) message; a radio resource control (RRC) configuration message.

[0040] According to this embodiment, the first message can be a NAS message or an RRC configuration message. Thus, the NCC value configured by the first network element for the terminal can be carried in the NAS message or the RRC configuration message. Since both NAS messages and RRC configuration messages are protected messages, carrying the security-related NCC value in the NAS message or the RRC configuration message enhances the security of the communication system.

[0041] In conjunction with some embodiments of the first aspect, in some embodiments, the first information may include at least one of the following: an initial NCC value; an updated NCC value.

[0042] In conjunction with some embodiments of the first aspect, in some embodiments, the initial NCC value may be determined by the access network device.

[0043] According to this embodiment, during the handover preparation phase, particularly LTM handover, an initial NCC value can be configured for the terminal. This initial NCC value can be determined and configured for the terminal by the access network equipment. In this way, the terminal can be prepared for the first handover.

[0044] In conjunction with some embodiments of the first aspect, in some embodiments, the first information for configuring NCC for the terminal can satisfy at least one of the following: the initial NCC value is configured by the access network device through an RRC configuration message; the updated NCC value is configured by the core network device through a NAS message; or the updated NCC value is configured by the access network device through an RRC configuration message.

[0045] According to this embodiment, the NCC can be configured to the terminal by the access network device via an RRC configuration message, or by the core network device via a NAS message. In this way, the terminal can obtain the NCC value from at least one of the access network device and the core network device, thereby ensuring the implementation of terminal handover.

[0046] In conjunction with some embodiments of the first aspect, in some embodiments, the above method may further include: receiving a second message sent by an access network device, wherein the second message is used to instruct the terminal to switch to another access network device.

[0047] In conjunction with some embodiments of the first aspect, in some embodiments, the second message may include first indication information, which is used to indicate the key update type to the terminal.

[0048] In conjunction with some embodiments of the first aspect, in some embodiments, the key update type may include at least one of the following: by K AMF Updated; by K gNB Update; updated by the next hop (NH).

[0049] In conjunction with some embodiments of the first aspect, in some embodiments, the above method may further include: determining the key update type; and performing NCC-based key update synchronization according to the key update type.

[0050] In a second aspect, embodiments of this disclosure provide a communication method. This method is performed by a core network device. The method includes: sending a first message to a terminal, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0051] According to this embodiment, the core network device can send a first message to the terminal. The first information carried in the first message can be used to configure the NCC for the terminal. In this way, the terminal can obtain the updated NCC, thereby ensuring the implementation of terminal handover.

[0052] In conjunction with some embodiments of the second aspect, in some embodiments, the NCC can be used to implement LTM handover of the terminal.

[0053] In conjunction with some embodiments of the second aspect, in some embodiments, the first message may be a NAS message.

[0054] In conjunction with some embodiments of the second aspect, in some embodiments, the first information may include an updated NCC value.

[0055] In conjunction with some embodiments of the second aspect, in some embodiments, the above method may further include: receiving a third message sent by the access network device, wherein the third message is used to request N2 path handover; and sending a fourth message to the access network device, wherein the fourth message is used to confirm that N2 path handover has been completed.

[0056] In conjunction with some embodiments of the second aspect, in some embodiments, the fourth message may include at least one of the following: an updated NCC value; and an NH value corresponding to the updated NCC value.

[0057] In conjunction with some embodiments of the second aspect, in some embodiments, the third message may include second indication information, which is used to instruct the access network device to perform LTM handover.

[0058] In a third aspect, embodiments of this disclosure provide a communication method. This method is performed by an access network device. The method includes: sending a first message to a terminal, wherein the first message carries first information, the first information being used to configure an NCC (Network Control Center) for the terminal.

[0059] According to this embodiment, the access network device can send a first message to the terminal. The first information carried in the first message can be used to configure the NCC for the terminal. In this way, the terminal can obtain the updated NCC, thereby ensuring the implementation of terminal handover.

[0060] In conjunction with some embodiments of the third aspect, in some embodiments, the NCC can be used to implement LTM handover of the terminal.

[0061] In conjunction with some embodiments of the third aspect, in some embodiments, the first message may be an RRC configuration message.

[0062] In conjunction with some embodiments of the third aspect, in some embodiments, the first information may include at least one of the following: an initial NCC value; an updated NCC value.

[0063] In conjunction with some embodiments of the third aspect, in some embodiments, the initial NCC value is determined by the access network device, and the updated NCC value is obtained by the access network device from the core network device.

[0064] In conjunction with some embodiments of the third aspect, in some embodiments, the first information for configuring NCC for the terminal can satisfy at least one of the following: the initial NCC value is configured by the access network device through an RRC configuration message; the updated NCC value is configured by the access network device through an RRC configuration message.

[0065] In conjunction with some embodiments of the third aspect, in some embodiments, the above method may further include: determining the trigger for LTM handover of the terminal; sending a second message to the terminal, wherein the second message is used to instruct the terminal to handover to another access network device.

[0066] In conjunction with some embodiments of the third aspect, in some embodiments, the second message may include first indication information, which is used to indicate the key update type to the terminal.

[0067] In conjunction with some embodiments of the third aspect, in some embodiments, the key update type may include at least one of the following: by K AMF Updated; by K gNB Updated; updated by NH.

[0068] In conjunction with some embodiments of the third aspect, in some embodiments, the above method may further include: sending a third message to the core network device, wherein the third message is used for N2 path handover; and receiving a fourth message sent by the core network device, wherein the fourth message is used to determine that the N2 path handover has been completed.

[0069] In conjunction with some embodiments of the third aspect, in some embodiments, the fourth message may include at least one of the following: an updated NCC value; and an NH value corresponding to the updated NCC value.

[0070] In conjunction with some embodiments of the third aspect, in some embodiments, the third message may include second indication information, which is used to instruct the access network device to perform LTM handover.

[0071] In a fourth aspect, embodiments of this disclosure provide a communication device. This device is disposed in a terminal. The device includes a transceiver module. The transceiver module is configured to: receive a first message sent by a first network element, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0072] In conjunction with some embodiments of the fourth aspect, in some embodiments, the NCC can be used to implement LTM handover of the terminal.

[0073] In conjunction with some embodiments of the fourth aspect, in some embodiments, the first network element may include at least one of the following: core network equipment; access network equipment.

[0074] In conjunction with some embodiments of the fourth aspect, in some embodiments, the first message may include at least one of the following: a NAS message; an RRC configuration message.

[0075] In conjunction with some embodiments of the fourth aspect, in some embodiments, the first information may include at least one of the following: an initial NCC value; an updated NCC value.

[0076] In conjunction with some embodiments of the fourth aspect, in some embodiments, the initial NCC value may be determined by the access network device.

[0077] In conjunction with some embodiments of the fourth aspect, in some embodiments, the first information for configuring NCC for the terminal can satisfy at least one of the following: the initial NCC value is configured by the access network device through an RRC configuration message; the updated NCC value is configured by the core network device through a NAS message; or the updated NCC value is configured by the access network device through an RRC configuration message.

[0078] In conjunction with some embodiments of the fourth aspect, in some embodiments, the transceiver module may also be configured to: receive a second message sent by an access network device, wherein the second message is used to instruct the terminal to switch to another access network device.

[0079] In conjunction with some embodiments of the fourth aspect, in some embodiments, the second message may include first indication information, which is used to indicate the key update type to the terminal.

[0080] In conjunction with some embodiments of the fourth aspect, in some embodiments, the key update type may include at least one of the following: by K AMF Updated; by K gNB Updated; updated by NH.

[0081] In conjunction with some embodiments of the fourth aspect, in some embodiments, the above-described apparatus may further include a processing module. The processing module is configured to: determine the key update type; and, based on the key update type, perform NCC-based key update synchronization.

[0082] In a fifth aspect, embodiments of this disclosure provide a communication device. The device is disposed in a core network device. The device includes a transceiver module. The transceiver module is configured to send a first message to a terminal, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0083] In conjunction with some embodiments of the fifth aspect, in some embodiments, the NCC can be used to implement LTM handover of the terminal.

[0084] In conjunction with some embodiments of the fifth aspect, in some embodiments, the first message may be a NAS message.

[0085] In conjunction with some embodiments of the fifth aspect, in some embodiments, the first information may include an updated NCC value.

[0086] In conjunction with some embodiments of the fifth aspect, in some embodiments, the transceiver module may also be configured to: receive a third message sent by the access network device, wherein the third message is used to request N2 path switching; and send a fourth message to the access network device, wherein the fourth message is used to confirm that N2 path switching has been completed.

[0087] In conjunction with some embodiments of the fifth aspect, in some embodiments, the fourth message may include at least one of the following: an updated NCC value; and an NH value corresponding to the updated NCC value.

[0088] In conjunction with some embodiments of the fifth aspect, in some embodiments, the third message may include second indication information, which is used to instruct the access network device to perform LTM handover.

[0089] In a sixth aspect, embodiments of this disclosure provide a communication apparatus. The apparatus is disposed in an access network device. The apparatus includes a transceiver module. The transceiver module is configured to send a first message to a terminal, wherein the first message carries first information, the first information being used to configure NCC for the terminal.

[0090] In conjunction with some embodiments of the sixth aspect, in some embodiments, the NCC can be used to implement LTM handover of the terminal.

[0091] In conjunction with some embodiments of the sixth aspect, in some embodiments, the first message may be an RRC configuration message.

[0092] In conjunction with some embodiments of the sixth aspect, in some embodiments, the first information may include at least one of the following: an initial NCC value; an updated NCC value.

[0093] In conjunction with some embodiments of the sixth aspect, in some embodiments, the initial NCC value is determined by the access network device, and the updated NCC value is obtained by the access network device from the core network device.

[0094] In conjunction with some embodiments of the sixth aspect, in some embodiments, the first information for configuring NCC for the terminal can satisfy at least one of the following: the initial NCC value is configured by the access network device through an RRC configuration message; the updated NCC value is configured by the access network device through an RRC configuration message.

[0095] In conjunction with some embodiments of the sixth aspect, in some embodiments, the above-described apparatus may further include a processing module. The processing module may be configured to: determine whether to trigger an LTM handover of the terminal. The transceiver module may also be configured to: send a second message to the terminal, wherein the second message is used to instruct the terminal to handover to another access network device.

[0096] In conjunction with some embodiments of the sixth aspect, in some embodiments, the second message may include first indication information, which is used to indicate the key update type to the terminal.

[0097] In conjunction with some embodiments of the sixth aspect, in some embodiments, the key update type may include at least one of the following: by K AMF Updated; by K gNB Updated; updated by NH.

[0098] In conjunction with some embodiments of the sixth aspect, in some embodiments, the transceiver module may also be configured to: send a third message to the core network device, wherein the third message is used for N2 path handover; and receive a fourth message sent by the core network device, wherein the fourth message is used to determine that the N2 path handover has been completed.

[0099] In conjunction with some embodiments of the sixth aspect, in some embodiments, the fourth message may include at least one of the following: an updated NCC value; and an NH value corresponding to the updated NCC value.

[0100] In conjunction with some embodiments of the sixth aspect, in some embodiments, the third message may include second indication information, which is used to instruct the access network device to perform LTM handover.

[0101] In a seventh aspect, embodiments of this disclosure provide a communication device. The communication device includes: one or more processors; and a memory storing instructions. When executed by the communication device, the instructions cause the communication device to implement the communication method as described in any of the first, second, third, and possible embodiments thereof.

[0102] In an eighth aspect, embodiments of this disclosure provide a communication system. The communication system includes at least one of the following: a terminal, a core network device, and an access network device. The terminal is used to implement the communication method as described in any of the first aspect and its possible embodiments. The core network device is used to implement the communication method as described in any of the second aspect and its possible embodiments. The access network device is used to implement the communication method as described in any of the third aspect and its possible embodiments.

[0103] In a ninth aspect, embodiments of this disclosure provide a storage medium. The storage medium stores instructions. When executed on a communication device, the instructions cause the communication device to perform the communication method as described in any of the first, second, third, and possible embodiments thereof.

[0104] In a tenth aspect, embodiments of this disclosure provide a program product. When executed by a communication device, the program product causes the communication device to perform the communication method as described in any of the first, second, third, and possible embodiments thereof.

[0105] In an eleventh aspect, embodiments of this disclosure provide a computer program. When this computer program is run on a computer, it causes the computer to perform the communication methods described in any of the first, second, third, and possible embodiments thereof.

[0106] In a twelfth aspect, embodiments of this disclosure provide a chip or chip system. The chip or chip system includes processing circuitry. The processing circuitry is configured to perform the communication methods described in any of the first, second, third, and possible embodiments thereof.

[0107] It is understood that the aforementioned communication devices, communication equipment, communication systems, storage media, program products, computer programs, chips, and chip systems are all used to execute the methods provided 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.

[0108] This disclosure provides a communication method and apparatus, a communication device, a communication system, a storage medium, and a program product. In some embodiments, terms such as communication method, information processing method, and information transmission method can be used interchangeably; terms such as communication device, communication device, network device, network function, and network entity can be used interchangeably; and terms such as communication system and information processing system can be used interchangeably.

[0109] 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.

[0110] In the embodiments disclosed herein, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of the various 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.

[0111] 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.

[0112] In the embodiments of this disclosure, unless otherwise stated, elements expressed in the singular form, such as “a,” “one,” “a kind,” “the,” “the,” “the,” “the,” “the,” “the,” “the,” “the,” “this,” etc., can mean “one and only one,” or “one or more,” “at least one,” etc. For example, when articles such as “a,” “an,” and “the” are used in translation, the noun following the article can be understood as either a singular or a plural expression.

[0113] In the embodiments of this disclosure, "a plurality of" means two or more.

[0114] In some embodiments, terms such as “at least one (at least one, at least one item, at least one)” and “one or more” may be used interchangeably.

[0115] 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 (executed regardless of B); in some embodiments, B (executed regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed); in some embodiments, both A and B are executed. The same applies when there are more branches such as A, B, C, etc.

[0116] 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.

[0117] 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. As another example, if the object being described is "information", then "second information" and "first information" can be the same information or different information, and their content can be the same or different.

[0118] In some embodiments, “including A,” “containing A,” “for indicating A,” and “carrying A” can be interpreted as directly carrying A or indirectly indicating A.

[0119] In some embodiments, the terms “in response to…”, “in response to determining…”, “in the case of…”, “when…”, “if…”, “if…”, etc., can be used interchangeably.

[0120] In some embodiments, the terms “greater than,” “greater than or equal to,” “not less than,” “more than,” “more than or equal to,” “not less than,” “higher than,” “higher than or equal to,” “not lower than,” and “above” can be used interchangeably, as can the terms “less than,” “less than or equal to,” “not greater than,” “less than,” “less than or equal to,” “not more than,” “lower than,” “lower than or equal to,” “not higher than,” and “below”.

[0121] In some embodiments, devices, etc., can be interpreted as physical or virtual, and their names are not limited to the names recorded in the embodiments. Terms such as “device”, “equipment”, “circuit”, “network element”, “node”, “function”, “unit”, “section”, “system”, “network”, “chip”, “chip system”, “entity”, and “subject” can be used interchangeably.

[0122] In some embodiments, "network" can be interpreted as devices and / or equipment included in the network (e.g., access network equipment, core network equipment, etc.).

[0123] In some embodiments, the terms "access network device (AN device)," "radio access network device (RAN device)," "base station (BS)," "radio base station," "fixed station," "node," "access point," "transmission point (TP)," "reception point (RP)," "transmission / reception point (TRP)," "panel," "antenna panel," "antenna array," "cell," "macro cell," "small cell," "femto cell," "pico cell," "sector," "cell group," "serving cell," "carrier," "component carrier," and "bandwidth part (BWP)" can be used interchangeably.

[0124] In some embodiments, the terms "terminal", "terminal device", "user equipment (UE)", "user terminal", "mobile station (MS)", "mobile terminal (MT)", "subscriber station", "mobile unit", "subscriber unit", "wireless unit", "remote unit", "mobile device", "wireless device", "wireless communication device", "remote device", "mobile subscriber station", "access terminal", "mobile terminal", "wireless terminal", "remote terminal", "handset", "user agent", "mobile client", and "client" can be used interchangeably.

[0125] In some embodiments, access network devices, core network devices, or network devices can be replaced by terminals. For example, embodiments of this disclosure can also be applied to structures where communication between access network devices, core network devices, or network devices and terminals is replaced by communication between multiple terminals (e.g., device-to-device (D2D), vehicle-to-everything (V2X), etc.). In this case, the structure can also be configured such that the terminal has all or part of the functions of the access network device. Furthermore, terms such as "uplink" and "downlink" can be replaced with terms corresponding to communication between terminals (e.g., "sidelink"). For example, uplink channel, downlink channel, etc., can be replaced with sidelink channel, and uplink link, downlink, etc., can be replaced with sidelink link.

[0126] In some embodiments, the terminal may be replaced by an access network device, a core network device, or a network device. In this case, the access network device, core network device, or network device may also be configured to have all or some of the functions of the terminal.

[0127] In some embodiments, the acquisition of data, information, etc., may comply with the laws and regulations of the country where the location is situated.

[0128] In some embodiments, data, information, etc., may be obtained with the user's consent.

[0129] 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.

[0130] Figure 1 is a schematic diagram of the architecture of a communication system provided according to an embodiment of the present disclosure. As shown in Figure 1, the communication system 100 includes a terminal 101, an access network device 102, and a core network device 103.

[0131] In some embodiments, terminal 101 includes, but is not limited to, 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.

[0132] In some embodiments, the access network device 102 is, for example, a node or device that connects a terminal to a wireless network. The access network device 102 may include, but is not limited to, 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 radio 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.

[0133] In some embodiments, the technical solutions of this disclosure can be applied to Open Radio Access Network (Open RAN) architectures. 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.

[0134] In some embodiments, the access network device 102 may be composed of a central unit (CU) and a distributed unit (DU). The CU may also be called a control unit. The CU-DU structure can separate the protocol layer of the access network device. 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 and centrally controlled by the CU. However, this is not the only possibility.

[0135] In some embodiments, the number of access network devices 102 may be one or more.

[0136] In some embodiments, core network device 103 may be a single device, multiple devices, or a group of devices. In some embodiments, core network device 103 may include one or more network elements. In some embodiments, network elements may be virtual or physical. In one example, a network element may be a network function, etc. In another example, a network element may be a network function entity, network device, etc. It is understood that network elements, network functions, network function entities, network devices, etc., can be interchanged. In some embodiments, core network device 103 may include at least one of Evolved Packet Core (EPC), 5G Core Network (5GCN), and Next Generation Core (NGC).

[0137] In some embodiments, the core network device 103 may be, for example, a control plane network element.

[0138] In some implementations, core network equipment 103 may be, for example, an access and mobility management function (AMF).

[0139] In some embodiments, the core network device 103 may be used to perform mobility management, non-access stratum mobility management (NAS MM) signaling processing, NAS session management (SM) signaling routing, security anchors and security context management, etc., and the names are not limited thereto.

[0140] In some embodiments, the communication system 100 described above may be a 4G communication system or a 5G communication system. It should be noted that the communication system 100 may also be other communication systems, such as a 6G communication system, but this disclosure does not specifically limit it.

[0141] With the development of mobile communication technology, inter-cell mobility mechanisms based on Layer 1 (L1) / Layer 2 (L2) signaling have been introduced. L1 / L2-triggered mobility (LTM) can achieve inter-cell mobility management through L1 measurement and reporting, and L1 / L2 signaling instructing terminals to perform cell handover. In some cases, LTM can refer to the process by which the network can trigger a primary cell (Pcell) and / or primary secondary cell (PScell) handover based on L1 measurement results through the media access control (MAC) control element (CE). In some embodiments, this process may also be accompanied by a change in the master cell group (MCG) and / or secondary cell group (SCG).

[0142] In some embodiments, LTM can support both same-frequency mobility and different-frequency mobility.

[0143] In some embodiments, new radio (NR) mobility may include intra-site handover-based LTM and inter-site handover-based LTM. In some embodiments, intra-site handover-based LTM may include, for example, intra-DU handover. In some embodiments, intra-site handover-based LTM may include, for example, intra-CU and inter-DU handover. In some embodiments, inter-site handover-based LTM may include, for example, inter-CU handover.

[0144] In some embodiments, LTM based on CU handover can be applied to the following situations: (1) when dual connectivity (DC) is not configured, the CU acts as the master node (MN); (2) when NR-DC (new radio dual connectivity) is configured, the CU acts as the slave node (SN), and the MCG does not change; (3) when NR-DC is configured, the CU acts as the master node, and the SCG does not change or is released.

[0145] In some embodiments, LTM based on inter-CU handover may involve the CU of the initial access network device and multiple CUs of one or more candidate access network devices. In this case, the entire LTM process may include at least three stages.

[0146] In the first phase, LTM preparation can be achieved. This first phase can also be called the LTM preparation phase. Based on the L3 radio resource management (RRM) measurement report, the initial access network device can identify candidate cells and initiate inter-node interactions for LTM preparation between CUs. After the interaction, the initial access network device can provide LTM configuration to the terminal, which includes radio resource control (RRC) configurations for multiple candidate cells.

[0147] In the second phase, initial LTM execution can be performed. This second phase can also be referred to as the initial LTM execution phase. The terminal can send an L1 measurement report to the initial access network device. After receiving a cell handover command via the MAC CE, the terminal can hand over to a candidate access network device (e.g., the first candidate access network device). In some embodiments, to support LTM without a random access channel (RACH), downlink and uplink early synchronization can be performed between the terminal and the candidate cell before receiving the cell handover command.

[0148] In the third phase, subsequent LTM execution can be implemented. This third phase can be referred to as the subsequent LTM execution phase. The current serving access network device (e.g., the first candidate access network device in the second phase) can trigger subsequent LTM, thereby switching to another candidate access network device (e.g., the second candidate access network device).

[0149] In some embodiments, during handover for inter-CU mobility, synchronization of the access stratum (AS) security key between the target access network device and the terminal can be achieved through the next hop chaining counter (NCC). The NCC can be sent by the source access network device to the target access network device and the terminal in the RRC reconfiguration signaling.

[0150] In some embodiments, NCC can be used for LTM switching or other types of switching. The embodiments disclosed herein are not specifically limited.

[0151] Figure 2 shows a schematic diagram of key derivation. As shown in Figure 2, based on K... AMF The initial K can be derived. gNB .

[0152] In some embodiments, in the horizontal direction, for the case where NCC equals 0, the initial K gNBIt can be directly used as an active K gNB Based on effective K gNB K can be derived NG-RAN *. The obtained K NG-RAN *Can be used as a new effective K gNB In some embodiments, based on the new effective K gNB We can continue to deduce K NG-RAN *and used as effective K gNB .

[0153] In some embodiments, in the vertical direction, based on the initial K gNB and K AMF This allows us to obtain NH when NCC equals 1; subsequently, based on NH and K... AMF We can obtain NH when NCC equals 2; then, based on the obtained NH and K AMF This gives us NH when NCC equals 3, and so on.

[0154] In some embodiments, in the horizontal direction, for the cases of NCC2 and NCC3, K can be derived based on the corresponding NH values. NG- RAN *. The obtained K NG-RAN *Can be used as a new effective K gNB In some embodiments, based on the new effective K gNB We can continue to deduce K NG-RAN *and used as effective K gNB .

[0155] In some embodiments, where an initial AS security context needs to be established between the terminal and the initial access network device, the AMF and the terminal can deduce K. gNB and NH parameters. NCC with each K gNB Associated with the NH parameter. With each K gNB The associated NCC can correspond to the NH value used to derive that NCC.

[0156] In some embodiments, such as during Xn handover, if the source access network device has an unused {NH, NCC} pair, the source access network device can perform key derivation in the vertical direction. In some embodiments, in the case of key derivation in the horizontal direction, the source access network device can perform key derivation based on the currently valid K. gNB Calculate K NB-RAN *. In some embodiments, in the case of key derivation in the vertical direction, the source access network device can calculate K based on NH. NB-RAN *

[0157] In some embodiments, the source access network device can {K NB-RAN *, NCC} is sent to the target access network device. The target access network device can then receive the K NB-RAN *Directly used for terminal K gNB The target access network device can compare the NCC value received from the source access network device with K. gNB Related. The target access network device can include the received NCC in the handover command message. The handover command message can be sent to the source access network device and forwarded to the terminal by the target access network device.

[0158] In some embodiments, the source access network device can be the initial access network device in the LTM, and the target access network device can be the first candidate access network device in the LTM. The handover process from the source access network device to the target access network device can be completed in the aforementioned second phase.

[0159] In some embodiments, the source access network device can be the first candidate access network device in the LTM, and the target access network device can be the second candidate access network device in the LTM. The handover process from the source access network device to the target access network device can be completed in the aforementioned third stage.

[0160] In some embodiments, the NCC value in the handover command message received by the terminal from the target access network device via the source access network device is equal to the current valid K. gNB In the case of the associated NCC value, the terminal can base its decision on the current valid K. gNB And the target physical cell identity (PCI) and its downlink frequency derivation K. NG-RAN *

[0161] In some embodiments, the NCC value in the handover command message received by the terminal from the target access network device via the source access network device is not equal to the currently valid K. gNB In the case of associated NCC values, the terminal can synchronize its local NH parameters through calculation. Simultaneously, the terminal can increase the NCC value until it matches the received NCC value. If the NCC values ​​match, the terminal can deduce K based on the synchronized NH parameters, the target PCI, and its downlink frequency. NG-RAN *

[0162] In some embodiments, the terminal may use K when communicating with the target access network device. NG-RAN *As K gNB .

[0163] During the switching process, such as NCC, K NG-RANSecurity-related configurations such as * can be synchronized between the source and target access network devices. Subsequently, during each handover, the source access network device can send the NCC to the terminal in an RRC configuration message, allowing the terminal to use the NCC for key rekeying synchronization with the target access network device.

[0164] Therefore, how to achieve key update synchronization during the LTM process is an urgent problem to be solved.

[0165] Figure 3A is an interactive schematic diagram of a communication method provided according to an embodiment of the present disclosure. The communication method involved in this embodiment can be applied to a communication system 100. As shown in Figure 3A, the communication method of this embodiment includes steps S3101 to S3113.

[0166] In some embodiments, the process shown in FIG3A may involve the terminal 101 switching from the first access network 102A to the second access network device 102B.

[0167] In some embodiments, the switching may be an LTM switching.

[0168] In some embodiments, the first access network device 102A may be the initial access network device involved in LTM, and the second access network device 102B may be one of one or more candidate access network devices involved in LTM.

[0169] In some embodiments, the first access network device 102A may be one of one or more candidate access network devices involved in LTM, and the second access network device 102B may be another of one or more candidate access network devices involved in LTM.

[0170] In some embodiments, the first access network device 102A may be referred to as the source access network device, and the second access network device 102B may be referred to as the target access network device. In one example, for a handover, the first access network device 102A may be the source gNB or the serving gNB. In some embodiments, the second access network device 102B may be the target gNB or the candidate gNB.

[0171] In step S3101, the first access network device 102A sends a first message to the terminal 101.

[0172] In some embodiments, terminal 101 may receive a first message.

[0173] In some embodiments, step S3101 can be performed during the LTM preparation phase. In some embodiments, the first access network device 102A can be the initial access network device involved in LTM, and the second access network device 102B can be one of a plurality of candidate access network devices involved in LTM. In one example, the second access network device 102B can be the first candidate access network device.

[0174] In some embodiments, step S3101 can be performed during the LTM execution phase. In one example, step S3101 can be sent by the first access network device 102A to the terminal 101 in a previous LTM execution phase. In some embodiments, the first access network device 102A can be a candidate access network device involved in LTM, and the second access network device 102B can be another candidate access network device involved in LTM. In one example, the first access network device 102A can be a first candidate access network device. In one example, the second access network device 102B can be a second candidate access network device.

[0175] In some embodiments, the first message may be used to configure the terminal 101.

[0176] In some embodiments, the first message may be an RRC configuration message. In one example, the RRC configuration message may be an RRC reconfiguration message.

[0177] In some embodiments, the first message may include first information.

[0178] In some embodiments, the first information may be used to configure the NCC for the terminal. In some embodiments, the first information may be used to instruct the terminal on the NCC.

[0179] In some embodiments, the name of the first information is not limited, and it may be, for example, key synchronization information, key configuration information, key notification information, etc.

[0180] In some embodiments, the first information may include a first NCC value.

[0181] In some embodiments, the first NCC value can be used for key derivation corresponding to the first access network device 102A.

[0182] In some embodiments, the first NCC value may be at least one of the following: an initial NCC value or an updated NCC value. In some embodiments, the first information may include at least one of the following: an initial NCC value or an updated NCC value.

[0183] In some embodiments, step S3101 can be performed during the LTM preparation phase. In some embodiments, during the LTM preparation phase, the first access network device 102A can send a first message to the terminal 101 to configure the NCC for the terminal 101. In some embodiments, the first information in the first message can indicate an initial NCC value. In this way, the first access network device 102A can configure an initial NCC value for the terminal 101. In one example, the initial NCC value can be configured by the first access network device 102A via an RRC configuration message.

[0184] In some embodiments, the initial NCC value may be obtained by the first access network device 102A from the core network device 103 during the LTM preparation phase. In one example, the core network device 103 may determine the initial NCC value and send it to the first access network device 102A. In another example, the first access network device 102A may determine the initial NCC value to be configured for the terminal 101. Afterward, the first access network device 102A may send the determined initial NCC value to the terminal 101.

[0185] In some embodiments, step S3101 can be executed during the LTM execution phase. In one example, step S3101 can be executed in the previous LTM execution phase. For example, if the first access network device 102A is the access network device after the handover in the previous LTM execution phase, it can execute step S3101 in the last step of the previous LTM execution phase. In some embodiments, during the previous LTM execution phase, the first access network device 102A can send a first message to the terminal 101 to configure NCC for the terminal 101. In some embodiments, the first information in the first message can indicate an updated NCC value. In this way, the first access network device 102A can configure an updated NCC value for the terminal 101. In one example, the initial NCC value can be configured by the first access network device 102A through an RRC configuration message.

[0186] In some embodiments, the updated NCC value may be obtained by the first access network device 102A from the core network device 103 during the previous LTM execution phase. In one example, the core network device 103 may determine the updated NCC value and send the updated NCC value to the first access network device 102A.

[0187] In some embodiments, the first NCC value may be a fixed value. In some embodiments, the first access network device 102A may not have any unused NH, in which case the first NCC value may be a fixed value. In some embodiments, a fixed value can be understood as the value not changing or the value not changing. In some embodiments, if the first access network device 102A does not have any unused NH, the first NCC value may remain unchanged.

[0188] In some embodiments, during the LTM preparation phase, the first access network device 102A may not have any unused NH, and the first NCC value may be a fixed value. In some embodiments, during the LTM execution phase, the first access network device 102A may not have any unused NH, and the first NCC value may be a fixed value. In one example, the first access network device 102A may not have any NH, and the first NCC value may be a fixed value. In one example, this fixed value may be equal to 0.

[0189] In some embodiments, the first NCC value can be a variable value. In some embodiments, the first access network device 102A may have unused NH, then the first NCC value can be an updated value. In one example, if the first access network device 102A has unused NH, then the first NCC value can be an updated value. In one example, the fixed value can be equal to any positive integer.

[0190] In some embodiments, during the LTM preparation phase, the first access network device 102A may have unused NH, in which case the first NCC value may be an updated value. In some embodiments, during the LTM execution phase, the first access network device 102A may have unused NH, in which case the first NCC value may be an updated value. In one example, the first access network device 102A may not have NH, in which case the first NCC value may be a fixed value. In one example, this fixed value may be equal to 0.

[0191] In some embodiments, the first message may also carry the cell identifiers of all candidate access network devices. In some embodiments, the first message may carry the cell identifiers of all cells of all candidate access network devices, including the second access network device 102B. In some embodiments, the first message in the LTM preparation phase may carry the cell identifiers of all candidate access network devices.

[0192] In some embodiments, the cell identifier carried in the first message can be used by terminal 101 to determine whether LTM handover is an inter-CU handover or an intra-CU handover.

[0193] In step S3102, terminal 101 sends a measurement report to the first access network device 102A.

[0194] In some embodiments, the first access network device 102A may receive measurement reports.

[0195] In some embodiments, the terminal 101 may perform measurement reporting while it is moving. In some embodiments, the terminal 101 may perform L1 measurement reporting.

[0196] In some embodiments, during the process of the terminal 101 moving from the coverage area of ​​the first access network device 102A to the coverage area of ​​the second access network 102B, the terminal 101 may perform L1 measurement and send an L1 / L2 measurement report to the first access network 102A.

[0197] In some embodiments, the measurement report may include at least one of the following: measurement results for the first access network device 102A and measurement results for the second access network device 102B. In some embodiments, the measurement report may include at least one of the following: measurement results for the first access network device 102A and measurement results for at least one candidate access network device. Measurement results for at least one candidate access network device may include measurement results for the second access network device 102B.

[0198] In some embodiments, L1 measurement reporting may be for at least one of the following measurements: signal to interference plus noise ratio (SINR) and reference signal receiving power (RSRP). It is understood that L1 measurement reporting may also be for other measurements, and this disclosure does not specifically limit this.

[0199] In step S3103, the first access network device 102A determines that an LTM handover has been triggered.

[0200] In some embodiments, the first access network device 102A may determine to trigger an LTM handover based on a measurement report.

[0201] In some embodiments, the first access network device 102A may determine, based on a measurement report, to trigger an LTM handover from the first access network device 102A to the second access network device 102B.

[0202] In some embodiments, the first access network device 102A may select the second access network device 102B as the target access network device for LTM handover based on a measurement report. In one example, the second access network device 102B may be selected by the first access network device 102A from one or more candidate access network devices based on a measurement report.

[0203] In some embodiments, after determining the second access network device 102B, the first access network device 102A may determine to trigger an LTM handover.

[0204] In some embodiments, the first access network device 102A may determine to use a first NCC value. In some embodiments, the first access network device 102A may select a first NCC value. In some embodiments, the first access network device 102A may determine that the first NCC value to use may be configured for the terminal 101 in step S3101.

[0205] In some embodiments, if the first access network device 102A does not have any unused NH, the first access network device 102A can determine that the key update type is by K. gNB Perform an update (i.e., based on K) gNB (Update). At this time, the first NCC value can be a fixed value. In some embodiments, if the first access network device 102A does not have any unused NH, the first access network device 102A can perform horizontal key derivation. In one example, the first access network device 102A can perform key derivation based on K for the first access network device 102A. gNB Derivation of K NG-RAN * For example, the first access network device 102A can use a key derivation function (KDF) based on the cell ID and K of the second access network device 102B. gNB Derivation of K NG-RAN *

[0206] In some embodiments, when the first access network device 102A has unused NH, the first access network device 102A can determine that the key update type is an update performed by NH (i.e., an update based on NH). In this case, the first NCC value can be a changed value. In some embodiments, when the first access network device 102A has unused NH, the first access network device 102A can perform key deduction in the vertical direction. The unused NH can, for example, be a first NH value associated with the first NCC value. In one example, the first access network device 102A can deduce K based on the first NH value. NG-RAN For example, the first access network device 102A can use a key derivation function to deduce K based on the cell identifier and the first NH value of the second access network device 102B. NG-RAN *

[0207] In step S3104, the first access network device 102A sends a handover request to the second access network device 102B.

[0208] In some embodiments, the second access network device 102B may receive a handover request.

[0209] In some embodiments, a handover request can be used to request a handover to a second access network device 102B.

[0210] In some embodiments, a switching request may include at least one of the following: a first NCC value, K NG-RAN *

[0211] In some embodiments, the first access network device 102A may send a handover request to the second access network device 102B via an X2 link.

[0212] In some embodiments, the handover request can be a handover request message.

[0213] In step S3105, the second access network device 102B performs key derivation.

[0214] In some embodiments, in response to a handover request, the second access network device 102B may perform key deduction.

[0215] In some embodiments, the second access network device 102B may obtain the first NCC value and / or K from the handover request. NG-RAN *

[0216] In some embodiments, the switching request may include K NG-RAN * Then the second access network device 102B can K NG-RAN *Used for K in connection with the second access network device 102B gNB .

[0217] In step S3106, the second access network device 102B sends a handover response to the first access network device 102A.

[0218] In some embodiments, the second access network device 102B may send a handover response in response to a handover request.

[0219] In some embodiments, the first access network device 102A may receive a handover response.

[0220] In some embodiments, the switching response may include a first NCC value.

[0221] In some embodiments, the handover response can be a handover response message.

[0222] In some embodiments, the handover response may be a handover request acknowledgment message.

[0223] In step S3107, the first access network device 102A sends a second message to the terminal 101.

[0224] In some embodiments, terminal 101 may receive a second message.

[0225] In some embodiments, the second message may be used to determine a switch from the first access network device 102A to the second access network device 102B.

[0226] In some embodiments, the second message may be used to command terminal 101 to switch from the first access network device 102A to the second access network device 102B.

[0227] In some embodiments, the second message can be used by terminal 101 to perform key deduction.

[0228] In some embodiments, the second message may be a MAC CE message.

[0229] In some embodiments, the second message may include at least one of the following: identification information of the second access network device 102B and first indication information.

[0230] In some embodiments, the identification information of the second access network device 102B may include the identifier of the second access network device 102B.

[0231] In some embodiments, the first indication information may be used to indicate the key update type from the first access network device 102A to the second access network device 102B.

[0232] In some embodiments, the first indication information may be used by terminal 101 to determine the key update type.

[0233] In some embodiments, the name of the first indication information is not limited, and it may be, for example, type information, key update type information, key update type indication information, etc.

[0234] In some embodiments, the key update type may include at least one of the following: by K AMF Updated; by K gNB Updated; updated by NH.

[0235] In step S3108, terminal 101 performs key update synchronization.

[0236] In some embodiments, after receiving the second message, terminal 101 may perform key update synchronization.

[0237] In some embodiments, terminal 101 may perform key update synchronization based on the second message.

[0238] In some embodiments, terminal 101 may determine the key update type.

[0239] In some embodiments, terminal 101 may determine the key update type based on at least one of the following: first indication information.

[0240] In some embodiments, terminal 101 can determine the key update type based on first indication information. In one example, the first indication information may indicate that the key update type is determined by K. AMF If an update is performed, terminal 101 can determine from K AMF Generate a new K gNB In one example, the first indication information could indicate that the key update type is K. gNB If an update is performed, terminal 101 can determine from the existing K gNB Generate a new K gNB In one example, the first indication information could indicate that the key update type is an update performed by NH, then terminal 101 could determine that a new K is generated from an NH that has never been used. gNB .

[0241] In some embodiments, terminal 101 may determine to use a first NCC value. In some embodiments, terminal 101 may select a first NCC value. In some embodiments, the first NCC value determined by terminal 101 to be used may be the first NCC value sent to terminal 101 in step S3101.

[0242] In some embodiments, when the key update type is determined to be by K AMF In the case of an update, terminal 101 can use a key derivation function based on K. AMF And the uplink NAS count, to derive K NG-RAN *

[0243] In some embodiments, when the key update type is determined to be by K gNB In the event of an update, terminal 101 can perform key derivation in the horizontal direction. In some embodiments, in the horizontal direction, terminal 101 can employ a key derivation function based on K for the first access network device 102A. gNB The cell identifier of the second access network device 102B, from which K is derived. NG-RAN *

[0244] In some embodiments, if the key update type is determined to be an update performed by NH, terminal 101 can perform key update synchronization in the vertical direction. In some embodiments, terminal 101 can perform key update synchronization for NH and K. NG-RAN The derivation of *. In one example, terminal 101 can update the local NH to the first NH value. For example, terminal 101 can use a key derivation function to derive the first NH value based on the local NH value and the cell identifier of the second access network device 102B.

[0245] In some embodiments, key update synchronization may include key deduction. In some embodiments, during key update synchronization, terminal 101 may perform key deduction. In one example, terminal 101 may deduce K based on the obtained first NH value. NG-RAN For example, terminal 101 can use a key derivation function to deduce K based on the first NH value and the cell identifier of the second access network device 102B. NG-RAN *

[0246] In some embodiments, the local NH value used by terminal 101 to derive the first NH value can be a third NH value. In some embodiments, the third NH value can be pre-configured. In one example, if step S3101 is a step in the LTM preparation phase, the third NH value can be pre-configured. For example, the third NH value can be protocol-defined. In some embodiments, the third NH value can be generated by terminal 101 according to the corresponding NCC iteration. In one example, if step S3101 is a step in the previous LTM execution phase, the third NH value can be the NH value updated in the previous LTM execution phase.

[0247] In some embodiments, terminal 101 may disconnect from first access network device 102A and apply the configuration of second access network device 102B.

[0248] In some embodiments, terminal 101 can derive K NG-RAN *Used as a new K gNB In one example, terminal 101 can use the derived K. NG-RAN *As for K for the second access network device 102B gNB .

[0249] In step S3109, terminal 101 sends a fifth message to the second access network device 102B.

[0250] In some embodiments, the second access network device 102B may receive a fifth message.

[0251] In some embodiments, the fifth message may be used to indicate that the configuration of terminal 101 is complete.

[0252] In some embodiments, the fifth message may be used to indicate that the handover configuration for terminal 101 is complete.

[0253] In some embodiments, the fifth message may be an RRC reconfiguration complete message.

[0254] In step S3110, the second access network device 102B sends a third message to the core network device 1031.

[0255] In some embodiments, the core network device 1031 may receive a third message.

[0256] In some embodiments, the third message can be used to request an N2 path switch from the core network device 1031.

[0257] In some embodiments, the third message may be used to request an N2 path switch from the first access network device 102A to the second access network device 102B.

[0258] In some embodiments, the third message may be an N2 path switch request message.

[0259] In some embodiments, the third message may include second instruction information.

[0260] In some embodiments, the second indication information may be used to indicate an LTM handover from the first access network device 102A to the second access network device 102B.

[0261] In some embodiments, the second indication information can be used by the core network device 103 to send an update result to the terminal 101.

[0262] In some embodiments, the second indication information may be an LTM switching indication.

[0263] In step S3111, the core network device 1031 performs key update and synchronization.

[0264] In some embodiments, upon receiving a third message, the core network device 1031 may perform a key update synchronization.

[0265] In some embodiments, the core network device 1031 may perform key update synchronization based on a third message.

[0266] In some embodiments, in step S3111, the core network device 1031 may update at least one of the following: NH value, NCC value.

[0267] In some embodiments, the update of NH by the core network device 1031 may include: the core network device 1031 employing a key derivation function, based on the first NH value and K... AMF The derivation is performed to obtain a second NH value. In one example, the second NH value could be an updated NH value.

[0268] In some embodiments, updating the NCC value by the core network device 1031 may include increasing the NCC value from a first NCC value to a second NCC value. In some embodiments, the core network device 1031 may add a specific value to the first NCC value to obtain the second NCC value. In one example, the core network device 1031 may add 1 to the first NCC value to obtain the second NCC value. In one example, the second NCC value may be an updated NCC value.

[0269] In some embodiments, the core network device 1031 can obtain an update result through step S3111. In some embodiments, the update result may include at least one of the following: the updated NH value and the updated NCC value. In one example, the update result may include at least one of the following: a second NH value and a second NCC value.

[0270] In step S3112, the core network device 1031 sends a fourth message to the second access network device 102B.

[0271] In some embodiments, the second access network device 102B may receive a fourth message.

[0272] In some embodiments, the fourth message can be used to send an update result to the second access network device 102B.

[0273] In some embodiments, the fourth message may include at least one of the following: a second NH value and a second NCC value.

[0274] In some embodiments, the fourth message may be a response message to the third message.

[0275] In some embodiments, the fourth message may be a path switching response message.

[0276] In step S3113, the core network device 1031 sends a first message to the terminal 101.

[0277] In some embodiments, terminal 101 may receive a first message.

[0278] In some embodiments, the first message may be sent by the core network device 1031 in response to the second indication information in the third message.

[0279] In some embodiments, if it is determined that the third message contains second instruction information, the core network device 1031 may determine to send the first message to the terminal 101.

[0280] In some embodiments, the first message may be used to configure NCC for terminal 101.

[0281] In some embodiments, the first message may include first information, which is used to configure a second NCC value for terminal 101.

[0282] In some embodiments, the first message can be used to update the NCC of terminal 101. For example, the first message can be used to update the NCC of terminal 101 to a second NCC value. For example, the first message can be used to update the first NCC value in terminal 101 to a second NCC value.

[0283] In some embodiments, the first message may be a NAS message.

[0284] In some embodiments, the second NCC value may be carried in the switching NCC notification information segment of the NAS message.

[0285] In some embodiments, terminal 101 may obtain the updated NCC value, i.e., the second NCC value, based on the first message.

[0286] In some embodiments, through steps S3113 and S3112, terminal 101 and second access network device 102B can obtain a second NCC value. In this case, the second NCC value in terminal 101 and second access network device 102B can be used for key update synchronization in the next LTM handover (e.g., LTM handover from second access network device 102B to another access network device).

[0287] In some embodiments, steps S3102 to S3113 may be executed within the same LTM execution phase. In some embodiments, step S3101 may be executed before the LTM execution phase. For example, step S3101 may be a step in an LTM preparation phase preceding the LTM execution phase. For example, step S3101 may be a step in an LTM execution phase preceding the LTM execution phase.

[0288] In some embodiments, step S3113 may be performed at the end of the LTM execution phase to enable terminal 101 to obtain an updated NCC value (i.e., a second NCC value). This updated NCC value may be used as the first NCC value in the next LTM execution phase.

[0289] The communication method of this embodiment of the present disclosure is realized through steps S3101 to S3113.

[0290] The communication method involved in the embodiments of this disclosure may include at least one of steps S3101 to S3113. For example, step S3101 may be implemented as a standalone embodiment. For example, step S3113 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S3101 to S3113 are not limited thereto.

[0291] In some embodiments, the multiple steps in steps S3101 to S3113 may be interchanged or performed simultaneously. In one example, steps S3112 and S3113 may be interchanged or performed simultaneously.

[0292] In some embodiments, steps S3102 to S3113 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0293] In some embodiments, steps S3101 to S3112 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0294] In some embodiments, other alternative implementations may be described before or after the specification corresponding to FIG3A.

[0295] Figure 3B is an interactive schematic diagram of the communication method provided according to an embodiment of the present disclosure. The communication method involved in the embodiment of the present disclosure can be applied to the communication system 100. As shown in Figure 3B, the communication method of the embodiment of the present disclosure includes steps S3201 to S3213.

[0296] In some embodiments, the process shown in FIG3B may involve the terminal 101 switching from the first access network 102A to the second access network device 102B.

[0297] In some embodiments, the switching may be an LTM switching.

[0298] In some embodiments, the first access network device 102A may be the initial access network device involved in LTM, and the second access network device 102B may be one of one or more candidate access network devices involved in LTM.

[0299] In some embodiments, the first access network device 102A may be one of one or more candidate access network devices involved in LTM, and the second access network device 102B may be another of one or more candidate access network devices involved in LTM.

[0300] In some embodiments, the first access network device 102A may be referred to as the source access network device, and the second access network device 102B may be referred to as the target access network device. In one example, for a handover, the first access network device 102A may be the source gNB or the serving gNB. In some embodiments, the second access network device 102B may be the target gNB or the candidate gNB.

[0301] In step S3201, the first access network device 102A sends a first message to the terminal 101.

[0302] The optional implementation of step S3201 can be found in the optional implementation of step S3101 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0303] In step S3202, terminal 101 sends a measurement report to the first access network device 102A.

[0304] The optional implementation of step S3202 can be found in the optional implementation of step S3102 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0305] In step S3203, the first access network device 102A determines that an LTM handover has been triggered.

[0306] The optional implementation of step S3203 can be found in the optional implementation of step S3103 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0307] In step S3204, the first access network device 102A sends a handover request to the second access network device 102B.

[0308] The optional implementation of step S3204 can be found in the optional implementation of step S3104 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0309] In step S3205, the second access network device 102B performs key derivation.

[0310] The optional implementation of step S3205 can be found in the optional implementation of step S3105 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0311] In step S3206, the second access network device 102B sends a handover response to the first access network device 102A.

[0312] The optional implementation of step S3206 can be found in the optional implementation of step S3106 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0313] In step S3207, the first access network device 102A sends a second message to the terminal 101.

[0314] The optional implementation of step S3207 can be found in the optional implementation of step S3107 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0315] In step S3208, terminal 101 performs key update synchronization.

[0316] The optional implementation of step S3208 can be found in the optional implementation of step S3108 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0317] In step S3209, terminal 101 sends a fifth message to the second access network device 102B.

[0318] The optional implementation of step S3209 can be found in the optional implementation of step S3109 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0319] In step S3210, the second access network device 102B sends a third message to the core network device 1031.

[0320] In some embodiments, the core network device 1031 may receive a third message.

[0321] In some embodiments, the third message can be used to request an N2 path switch from the core network device 1031.

[0322] In some embodiments, the third message may be used to request an N2 path switch from the first access network device 102A to the second access network device 102B.

[0323] In some embodiments, the third message may be an N2 path switching request message.

[0324] In some embodiments, the third message may not contain the second instruction information.

[0325] In step S3211, the core network device 1031 performs key update and synchronization.

[0326] The optional implementation of step S3211 can be found in the optional implementation of step S3111 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0327] In step S3112, the core network device 1031 sends a fourth message to the second access network device 102B.

[0328] The optional implementation of step S3212 can be found in the optional implementation of step S3112 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0329] In step S3113, the second access network device 102B sends a first message to the terminal 101.

[0330] In some embodiments, terminal 101 may receive a first message.

[0331] In some embodiments, the first message may be used to configure the terminal 101.

[0332] In some embodiments, the first message may be an RRC configuration message. In one example, the RRC configuration message may be an RRC reconfiguration message.

[0333] In some embodiments, the first message may include first information, which is used to configure a second NCC value for terminal 101.

[0334] In some embodiments, the first message can be used to update the NCC of terminal 101. For example, the first message can be used to update the NCC of terminal 101 to a second NCC value. For example, the first message can be used to update the first NCC value in terminal 101 to a second NCC value.

[0335] In some embodiments, the first message may be an RRC configuration message.

[0336] In some embodiments, terminal 101 may obtain the updated NCC value, i.e., the second NCC value, based on the first message.

[0337] In some embodiments, through steps S3213 and S3212, both terminal 101 and second access network device 102B can obtain the second NCC value. In this case, the second NCC value in terminal 101 and second access network device 102B can be used for key update synchronization in the next LTM handover (e.g., LTM handover from second access network device 102B to another access network device).

[0338] In some embodiments, steps S3202 to S3213 may be executed within the same LTM execution phase. In some embodiments, step S3201 may be executed before the LTM execution phase. For example, step S3201 may be a step in an LTM preparation phase preceding the LTM execution phase. For example, step S3201 may be a step in an LTM execution phase preceding the LTM execution phase.

[0339] In some embodiments, step S3213 may be performed at the end of the LTM execution phase to enable terminal 101 to obtain an updated NCC value (i.e., a second NCC value). This updated NCC value may be used as the first NCC value in the next LTM execution phase.

[0340] The communication method of this embodiment of the present disclosure is realized through steps S3201 to S3213.

[0341] The communication method involved in the embodiments of this disclosure may include at least one of steps S3201 to S3213. For example, step S3201 may be implemented as a standalone embodiment. For example, step S3213 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S3201 to S3213 are not limited thereto.

[0342] In some embodiments, steps S3202 to S3213 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0343] In some embodiments, steps S3201 to S3212 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0344] In some embodiments, other optional implementations may be described before or after the specification corresponding to FIG3B.

[0345] 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.

[0346] In some embodiments, the terms “radio”, “wireless”, “radio access network (RAN)”, “access network (AN)”, and “RAN-based” can be used interchangeably.

[0347] 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.

[0348] In some embodiments, terms such as “send,” “transmit,” “report,” “distribute,” “transfer,” “bidirectional transmission,” “send and / or receive” can be used interchangeably.

[0349] 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.

[0350] In some embodiments, the determination or judgment can be made by a value represented by 1 bit (0 or 1), or by a true or false value (boolean), or by a comparison of numerical values ​​(e.g., a comparison with a predetermined value), but is not limited thereto.

[0351] In some embodiments, the terms "configuration" and "reconfiguration" can be used interchangeably.

[0352] Figure 4 is a flowchart illustrating a communication method provided according to an embodiment of the present disclosure. This disclosure relates to a communication method. This communication method is executed by terminal 101. As shown in Figure 4, the method includes steps S401 to S406.

[0353] In step S401, the first message is obtained.

[0354] The optional implementations of step S401 can be found in the optional implementations of step S3101 in Figure 3A and step S3201 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0355] In some embodiments, terminal 101 may receive a first message sent by the first access network device 102A, but is not limited thereto, and may also receive a first message sent by other entities.

[0356] In step S402, a measurement report is sent.

[0357] The optional implementations of step S402 can be found in the optional implementations of step S3102 in Figure 3A and step S3202 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0358] In some embodiments, terminal 101 may send measurement results to first access network device 102A, but is not limited to that, it may also send measurement results to other entities.

[0359] In step S403, the second message is obtained.

[0360] The optional implementations of step S403 can be found in the optional implementations of step S3107 in Figure 3A and step S3207 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0361] In some embodiments, terminal 101 may receive a second message sent by the first access network device 102A, but is not limited thereto, and may also receive a second message sent by other entities.

[0362] In step S404, key update and synchronization are performed.

[0363] The optional implementations of step S404 can be found in the optional implementations of step S3108 in Figure 3A and step S3208 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0364] In some embodiments, key synchronization updates can be performed based on a second message.

[0365] In step S405, the fifth message is sent.

[0366] The optional implementations of step S405 can be found in the optional implementations of step S3109 in Figure 3A and step S3209 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0367] In some embodiments, terminal 101 may send a fifth message to the second access network device 102B, but is not limited to that, it may also send a fifth message to other entities.

[0368] In step S406, the first message is obtained.

[0369] The optional implementations of step S406 can be found in the optional implementations of step S3113 in Figure 3A and step S3213 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0370] In some embodiments, terminal 101 may receive a first message sent by second access network device 102B, but is not limited thereto, and may also receive a first message sent by other entities.

[0371] In some embodiments, terminal 101 may receive a first message sent by core network device 103, but is not limited thereto, and may also receive a first message sent by other entities.

[0372] The communication method involved in the embodiments of this disclosure may include at least one of steps S401 to S406. For example, step S401 may be implemented as a standalone embodiment. For example, step S406 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S401 to S406 are not limited thereto.

[0373] In some embodiments, steps S402 to S406 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0374] In some embodiments, steps S401 to S405 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0375] Figure 5 is a flowchart illustrating a communication method provided according to an embodiment of the present disclosure. This disclosure relates to a communication method. This communication method is executed by a core network device 103. As shown in Figure 5, the method includes steps S501 to S504.

[0376] In step S501, the third message is obtained.

[0377] The optional implementations of step S501 can be found in the optional implementations of step S3110 in Figure 3A and step S3210 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0378] In some embodiments, the core network device 103 may receive a third message sent by the second access network device 102B, but is not limited thereto, and may also receive a third message sent by other entities.

[0379] In step S502, key update and synchronization are performed.

[0380] The optional implementation of step S502 can be found in the optional implementation of step S3111 in Figure 3A and step S3211 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0381] In some embodiments, key update synchronization can be performed based on a third message.

[0382] In step S503, a fourth message is sent.

[0383] The optional implementations of step S503 can be found in the optional implementations of step S3112 in Figure 3A and step S3212 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0384] In some embodiments, the core network device 103 may send a fourth message to the second access network device 102B, but is not limited to sending a fourth message to other entities.

[0385] In step S504, the first message is sent.

[0386] The optional implementation of step S504 can be found in the optional implementation of step S3113 in Figure 3A, as well as other related parts in the embodiments involved in Figure 3A, which will not be repeated here.

[0387] In some embodiments, the core network device 103 may send a first message to the terminal 101, but is not limited to that, it may also send a first message to other entities.

[0388] The communication method involved in the embodiments of this disclosure may include at least one of steps S501 to S504. For example, step S503 may be implemented as a standalone embodiment. For example, step S504 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S501 to S504 are not limited thereto.

[0389] In some embodiments, steps S501, S502, and S503 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0390] In some embodiments, steps S501, S502, and S504 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0391] Figure 6A is a schematic flowchart of a communication method provided according to an embodiment of the present disclosure. This disclosure relates to a communication method. The communication method is executed by a first access network device 102A. As shown in Figure 6A, the method includes steps S6101 to S6106.

[0392] In step S6101, the first message is sent.

[0393] The optional implementation of step S6101 can be found in the optional implementation of step S3101 in Figure 3A and step S3201 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0394] In some embodiments, the first access network device 102A may send a first message to the terminal 101, but is not limited to that, it may also send a first message to other entities.

[0395] In step S6102, the measurement results are obtained.

[0396] The optional implementations of step S6102 can be found in the optional implementations of step S3102 in Figure 3A and step S3202 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0397] In some embodiments, the first access network device 102A may receive measurement results sent by the terminal 101, but is not limited thereto, and may also receive measurement results sent by other entities.

[0398] In step S6103, it is determined that an LTM switch will be triggered.

[0399] The optional implementation of step S6103 can be found in the optional implementation of step S3103 in Figure 3A and step S3203 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0400] In step S6104, a handover request is sent.

[0401] The optional implementations of step S6104 can be found in the optional implementations of step S3104 in Figure 3A and step S3204 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0402] In some embodiments, the first access network device 102A may send a handover request to the second access network device 102B, but is not limited to that, it may also send a handover request to other entities.

[0403] In some embodiments, a handover request may be used to trigger a second access network device 102B to perform a key deduction.

[0404] In step S6105, the switching response is obtained.

[0405] The optional implementations of step S6105 can be found in the optional implementations of step S3106 in Figure 3A and step S3206 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0406] In some embodiments, the first access network device 102A may receive a handover response sent by the second access network device 102B, but is not limited thereto, and may also receive a handover response sent by other entities.

[0407] In step S6106, a second message is sent.

[0408] Optional implementations of step S6106 can be found in optional implementations of step S3107 in Figure 3A and step S3207 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0409] In some embodiments, the first access network device 102A may send a second message to the terminal 101, but is not limited to that, it may also send a second message to other entities.

[0410] In some embodiments, the second message may be used to determine a switch from the first access network device 102A to the second access network device 102B.

[0411] The communication method involved in the embodiments of this disclosure may include at least one of steps S6101 to S6106. For example, step S6101 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S6101 to S6106 are not limited thereto.

[0412] In some embodiments, steps S6102, S6103, S6104, S6105, and S6106 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0413] Figure 6B is a schematic flowchart of a communication method provided according to an embodiment of the present disclosure. This disclosure relates to a communication method. The communication method is executed by a second access network device 102B. As shown in Figure 6B, the method includes steps S6201 to S6207.

[0414] In step S6201, a handover request is obtained.

[0415] The optional implementation of step S6201 can be found in the optional implementation of step S3104 in Figure 3A and step S3204 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0416] In some embodiments, the second access network device 102B may receive a handover request sent by the first access network device 102A, but is not limited thereto, and may also receive a handover request sent by other entities.

[0417] In step S6202, key derivation is performed.

[0418] Optional implementations of step S6202 can be found in step S3105 of Figure 3A and step S3205 of Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0419] In some embodiments, key derivation can be performed in response to a handover request.

[0420] In step S6203, a handover response is sent.

[0421] The optional implementations of step S6203 can be found in the optional implementations of step S3106 in Figure 3A and step S3206 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0422] In some embodiments, the second access network device 102B may send a handover response to the first access network device 102A, but is not limited thereto, and may also send a handover response to other entities.

[0423] In step S6204, the fifth message is obtained.

[0424] The optional implementation of step S6204 can be found in the optional implementation of step S3109 in Figure 3A and step S3209 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0425] In some embodiments, the second access network device 102B may receive a fifth message sent by the terminal 101, but is not limited thereto, and may also receive a fifth message sent by other entities.

[0426] In step S6205, a third message is sent.

[0427] The optional implementation of step S6205 can be found in the optional implementation of step S3110 in Figure 3A and step S3210 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0428] In some embodiments, the second access network device 102B may send a third message to the core network device 103, but is not limited thereto; it may also send a third message to other entities.

[0429] In step S6206, the fourth message is obtained.

[0430] The optional implementation of step S6206 can be found in the optional implementation of step S3112 in Figure 3A and step S3212 in Figure 3B, as well as other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0431] In some embodiments, the second access network device 102B may receive a fourth message sent by the core network device 103, but is not limited thereto, and may also receive a fourth message sent by other entities.

[0432] In step S6207, the first message is sent.

[0433] The optional implementation of step S6207 can be found in the optional implementation of step S3213 in Figure 3B, as well as other related parts in the embodiments involved in Figure 3B, which will not be repeated here.

[0434] In some embodiments, the second access network device 102B may send a first message to the terminal 101, but is not limited thereto; it may also send a first message to other entities.

[0435] The communication method involved in the embodiments of this disclosure may include at least one of steps S6201 to S6207. For example, step S6207 may be implemented as a standalone embodiment. It should be noted that the possible standalone embodiments consisting of one or more steps S6201 to S6207 are not limited thereto.

[0436] In some embodiments, steps S6201, S6202, S6203, S6204, S6205, and S6206 are optional, and one or more of these steps may be omitted or substituted in different embodiments.

[0437] Figure 7 is an interactive schematic diagram of a communication method provided according to an embodiment of the present disclosure. This disclosure relates to a communication method. As shown in Figure 7, the method includes step S701.

[0438] In step S701, the first network element sends a first message to the terminal 101.

[0439] The optional implementations of step S701 can be found in the optional implementations of steps S3101 and S3113 in Figure 3A, steps S3201 and S3213 in Figure 3B, and other related parts in the embodiments involved in Figures 3A and 3B, which will not be repeated here.

[0440] In some embodiments, the first network element may include at least one of the following: access network equipment and core network equipment.

[0441] In some embodiments, the first network element may include a first access network device 102A.

[0442] In some embodiments, the first network element may include a second access network device 102B.

[0443] In some embodiments, the first network element may include core network device 103.

[0444] In the following, the technical solutions of the embodiments of this disclosure will be described by way of specific implementation.

[0445] In some embodiments, this disclosure proposes that during the LTM preparation phase, the initial gNB configures the NCC value on the UE via RRC reconfiguration signaling. The configured NCC value is used for the next handover from the initial gNB to a candidate gNB. Subsequently, at each handover completion phase, the target gNB sends an LTM indication to the AMF (i.e., core network equipment) in an N2 path handover request. Upon receiving the LTM indication, and after deducing the NH and updating the corresponding NCC value, the AMF sends the new NCC value to the UE via NAS signaling. Simultaneously, an N2 path handover response containing the new NCC value and the newly deduced NH is sent to the target gNB.

[0446] In some embodiments, at the end of each handover, the UE and gNB (e.g., gNB1, which has switched from gNB0) can obtain an updated NCC value for key update synchronization for the next handover (e.g., a handover from gNB1 to gNB2).

[0447] Figure 8A is an interactive schematic diagram of an exemplary embodiment of the communication method provided according to the present disclosure. The communication method shown in Figure 8A may include steps 1 to 22.

[0448] In step 1, LTM preparation (i.e., the LTM preparation phase) is performed between the UE and the serving / source gNB, during which NCC1 is pre-configured for the UE via RRC reconfiguration messages. If the serving / source gNB has an unused NH, the configured NCC value, i.e., NCC1, is 1. If the serving / source gNB does not have an unused NH, the configured NCC value, i.e., NCC1, is 0. Simultaneously, the serving / source gNB can configure all cell IDs of candidate gNBs for the UE. Based on these cell IDs, the UE can distinguish between inter-CU handover and intra-CU handover.

[0449] In step 2, when the UE moves, the UE sends an L1 measurement report to the serving / source gNB.

[0450] In step 3, after selecting the target gNB (candidate gNB1), the serving / source gNB determines whether the LTM process needs to be triggered. If the serving / source gNB does not have any unused NH, then the serving / source gNB performs horizontal key derivation, i.e., based on K... gNB0 Derivation of K NB-RAN *(that is, K) NG-RAN *←KDF(K gNB0 Cell identifier). If the serving / source gNB has an unused NH (associated with NCC1), the serving / source gNB performs vertical key derivation, that is, derivation of K based on the unused NH. NB-RAN *(that is, K) NG-RAN*←KDF(NH1, Community Identifier)).

[0451] In step 4, the service / source gNB sends the derived K to candidate gNB1. NB-RAN *and for K NB-RAN *The derived NCC value (i.e., NCC1). gNB1 will K NB-RAN *Used as K gNB1 And return the NCC value (NCC1) to the service / source gNB.

[0452] In step 5, the serving / source gNB sends a MAC CE message to the UE, which indicates the target gNB (candidate gNB1). In some embodiments, the MAC CE may include an indication of the key update type (i.e., first indication information).

[0453] In step 6, upon receiving a MAC CE from the serving / source gNB, subsequent steps can be performed. In step 6a, the UE first determines the key update type based on the pre-configured cell identifier of the target gNB or based on an indication of the key update type received via the MAC CE message. If the indication is provided by K... AMF Update, UE performs derivation, i.e., K gNB =KDF(Uplink NAS count, K AMF In step 6b, if the instruction is given by K... gNB To perform the update, the UE performs horizontal key derivation (i.e., K... NG-RAN *←KDF(K gNB0 Cell identifier); If the indication is updated by NH, the UE chooses to perform vertical key derivation by the NCC1 pre-configured by the serving / source gNB during the LTM preparation phase, that is, to deduce NH and K. NG-RAN *(That is, NH1=KDF(NH,K) AMF ), K NG-RAN *←KDF(NH1, Cell Identifier)). In step 6c, the UE leaves the serving / source gNB and applies the configuration of the target gNB (candidate gNB1), including setting K... NG-RAN *K to be used for gNB1 gNB1 .

[0454] In step 7, the UE sends an RRC reconfiguration complete message to gNB1.

[0455] In step 8, the target gNB (gNB1) sends an N2 path handover request to the AMF, which includes an LTM handover indication (i.e., second indication information).

[0456] In step 9, upon receiving an N2 path switching request, the AMF updates NH (e.g., from NH1 to NH2) and increases the corresponding NCC value (e.g., from NCC1 to NCC2).

[0457] In step 10, AMF returns the new NH and NCC (i.e., NH2 and NCC2) to gNB1 in the N2 path switching response message.

[0458] In step 11, based on the LTM handover indication received in step 8, the AMF sends a new NCC value (NCC2) to the UE via NAS signaling.

[0459] In step 12, while the UE is in motion, the UE sends an L1 measurement report to the serving / source gNB (gNB1).

[0460] In step 13, after selecting the target gNB (candidate gNB2), the serving / source gNB (gNB1) determines whether the LTM process needs to be triggered. Since the serving / source gNB has unused NH (NH2 associated with NCC2), the serving / source gNB performs vertical key derivation, i.e., deriving K based on the unused NH. NB-RAN *(that is, K) NG-RAN *←KDF(NH2, Community Identifier)).

[0461] In some embodiments, if the serving / source gNB does not have any unused NH after a subsequent intra-CU handover is triggered, the serving / source gNB performs a horizontal key derivation, i.e., based on K. gNB1 Derivation of K NB-RAN *(that is, K) NG-RAN *←KDF(K gNB1 (Community signage)

[0462] In step 14, the service / source gNB (gNB1) sends the derived K to the candidate gNB2. NB-RAN *and for K NB-RAN *The derived NCC value (i.e., NCC2). gNB2 will K NB-RAN *Used as K gNB2 And return the NCC value (NCC2) to the service / source gNB.

[0463] In step 15, gNB1 sends a MAC CE message to the UE, which indicates the target gNB (candidate gNB2). In some embodiments, the MAC CE may include an indication of the key update type (i.e., first indication information).

[0464] In step 16, if a MAC CE is received from gNB1, subsequent steps can be performed. In step 16a, the UE first determines the handover key update type based on the pre-configured cell identifier of the target gNB or based on an indication of the key update type received via the MAC CE message. If the indication is from K... AMF Update, UE derivation K gNB =KDF(Uplink NAS count, K AMF In step 16b, if the instruction is given by K... gNB To perform the update, the UE performs horizontal key derivation (i.e., K... NG-RAN *←KDF(K gNB1 Cell identifier); If the indication is updated by NH, the UE selects the NCC2 received in step 12 for vertical key derivation, that is, derivation of NH and K. NG-RAN *(That is, NH2=KDF(NH1,K AMF ), K NG-RAN *←KDF(NH2, Cell Identifier)). In step 6c, the UE leaves the serving / source gNB and applies the configuration of the target gNB (candidate gNB2), including setting K... NG-RAN *Used as K for use against gNB2 gNB2 .

[0465] In step 17, the UE sends an RRC reconfiguration complete message to gNB2.

[0466] In step 18, the target gNB (gNB2) sends an N2 path handover request to the AMF, which includes an LTM handover indication (i.e., second indication information).

[0467] In step 19, upon receiving an N2 path switching request, the AMF updates NH (e.g., from NH2 to NH3) and increases the corresponding NCC value (e.g., from NCC2 to NCC3).

[0468] In step 20, AMF returns the new NH and NCC (i.e. NH3 and NCC3) to gNB2 in the N2 path switching response message.

[0469] In step 21, based on the LTM handover indication received in step 18, the AMF sends a new NCC value (NCC3) to the UE via NAS signaling.

[0470] In step 22, the subsequent process is performed.

[0471] In some embodiments, the updated NCC value can be sent by the gNB via RRC signaling.

[0472] In some embodiments, the target gNB may omit the LTM handover indication from the N2 path handover request. Upon receiving an N2 path handover response from the AMF, the target gNB may send the new NCC value received from the AMF to the UE via RRC reconfiguration signaling.

[0473] Figure 8B is an interactive schematic diagram of an exemplary implementation of the communication method provided according to embodiments of the present disclosure. The communication method shown in Figure 8B may include steps 1 to 22.

[0474] In some embodiments, some steps of the implementation shown in FIG8B are the same as those in the implementation in FIG8A, and will not be repeated here. Here, only the different steps will be described.

[0475] In step 8, the target gNB (gNB1) sends an N2 path switching request to the AMF.

[0476] In step 11, upon receiving the N2 path handover response, gNB1 forwards the NCC2 received from the AMF to the UE via RRC reconfiguration signaling.

[0477] In step 18, the target gNB (gNB2) sends an N2 path switching request to the AMF.

[0478] In step 21, upon receiving the N2 path handover response, gNB2 forwards the NCC3 received from AMF to the UE via RRC reconfiguration signaling.

[0479] In the embodiments disclosed herein, some or all of the steps and their optional implementations may be arbitrarily combined with some or all of the steps in other embodiments, or may be arbitrarily combined with the optional implementations in other embodiments.

[0480] This disclosure also provides communication apparatuses for implementing any of the above methods. For example, this disclosure provides a communication apparatus including units or modules for implementing the steps performed by a network element in any of the above methods. For example, this disclosure provides a communication apparatus including units or modules for implementing the steps performed by a terminal in any of the above methods.

[0481] 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.

[0482] 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, microprocessor, graphics processing unit (GPU) (which can be understood as a type of microprocessor), or 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 by an application-specific integrated circuit (ASIC) or a programmable logic device, 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), tensor processing unit (TPU), deep learning processing unit (DPU), etc.

[0483] Figure 9 is a schematic diagram of the structure of a communication device provided according to an embodiment of the present disclosure. As shown in Figure 9, the communication device 900 may include a transceiver module 901 and a processing module 902.

[0484] In some embodiments, the communication device 900 may be a terminal 101. In some embodiments, the transceiver module 901 may be configured to: receive a first message sent by a first network element, wherein the first message carries first information, and the first information is used to configure NCC for the terminal. Optionally, the transceiver module 901 may be configured to perform at least one of the communication steps such as sending and / or receiving performed by the terminal 101 in any of the above methods (e.g., steps S3101, 3102, S3107, S3109, S3113, S3201, 3202, S3207, S3209, S3213, but not limited thereto), which will not be elaborated here. Optionally, the processing module 902 may be configured to perform at least one of the steps other than the communication steps such as sending and / or receiving performed by the terminal 101 in any of the above methods (e.g., step S3108, but not limited thereto), which will not be elaborated here.

[0485] In some embodiments, the communication device 900 may be a core network device 103. In some embodiments, the transceiver module 901 may be configured to send a first message to a terminal, wherein the first message carries first information, and the first information is used to configure NCC for the terminal. Optionally, the transceiver module 901 may be configured to perform at least one of the communication steps such as sending and / or receiving performed by the core network device 103 in any of the above methods (e.g., steps S3110, S3112, S3113, S3210, S3212, but not limited thereto), which will not be elaborated here. Optionally, the processing module 902 may be configured to perform at least one of the steps other than the communication steps such as sending and / or receiving performed by the core network device 103 in any of the above methods (e.g., steps S3011, S3211, but not limited thereto), which will not be elaborated here.

[0486] In some embodiments, the communication device 900 may be an access network device 102. In some embodiments, the transceiver module 901 may be configured to send a first message to a terminal, wherein the first message carries first information, and the first information is used to configure NCC for the terminal. Optionally, the transceiver module 901 may be configured to perform at least one of the communication steps such as sending and / or receiving performed by the access network device 102 in any of the above methods (e.g., steps S3101, S3102, S3104, S3106, S3107, S3109, S3110, S3112, S3201, S3202, S3204, S3206, S3207, S3209, S3210, S3212, S3213, but not limited thereto), which will not be elaborated here. Optionally, the processing module 902 may be configured to perform at least one of the steps performed by the access network device 102 in any of the above methods, other than communication steps such as sending and / or receiving (e.g., steps S3103, S3105, S3203, S3205, but not limited thereto), which will not be described in detail here.

[0487] In some embodiments, the transceiver module may include a transmitting module and / or a receiving module. The transmitting and receiving modules may be separate or integrated. Optionally, the transceiver module may be interchangeable with a transceiver.

[0488] 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.

[0489] Figure 10A is a schematic diagram of the structure of a communication device provided according to an embodiment of the present disclosure. The communication device 10100 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 10100 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.

[0490] As shown in Figure 10A, the communication device 10100 includes one or more processors 10101. The processor 10101 can be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the communication device (e.g., base station, baseband chip, terminal device, terminal device chip, DU or CU, etc.), execute programs, and process program data. Optionally, the communication device 10100 can be used to execute any of the above methods. Optionally, one or more processors 10101 can be used to invoke instructions to cause the communication device 10100 to execute any of the above methods.

[0491] In some embodiments, the communication device 10100 further includes one or more transceivers 10102. When the communication device 10100 includes one or more transceivers 10102, the transceiver 10102 performs at least one of the communication steps such as sending and / or receiving in the above method (e.g., steps S3101, S3102, S3104, S3106, S3107, S3109, S3110, S3112, S3113, S3201, S3202, S3204, S3206, S3207, S3209, S3210, S3212, S3213, but not limited thereto), and the processor 10101 performs other steps (e.g., steps S3103, S3105, S3108, S3111, S3203, S3205, S3208, S3211, but not limited thereto). In optional embodiments, the transceiver may include a receiver and / or a transmitter, which may be separate or integrated. 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; and the terms receiver, receiving unit, receiver, receiving circuit, etc., can be used interchangeably.

[0492] In some embodiments, the communication device 10100 further includes one or more memories 10103 for storing data. Optionally, all or part of the memories 10103 may be located outside the communication device 10100. In optional embodiments, the communication device 10100 may include one or more interface circuits 10104. Optionally, the interface circuits 10104 are connected to the memories 10103 and can be used to receive data from the memories 10103 or other devices, and to send data to the memories 10103 or other devices. For example, the interface circuits 10104 can read data stored in the memories 10103 and send the data to the processor 10101.

[0493] The communication device 10100 described in the above embodiments may be a network device or a terminal, but the scope of the communication device 10100 described in this disclosure is not limited thereto, and the structure of the communication device 10100 may not be limited by FIG10A. The communication device may be a standalone device or may be 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 and programs; (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.

[0494] Figure 10B is a schematic diagram of the structure of a chip provided according to an embodiment of the present disclosure. For cases where the communication device 10100 can be a chip or a chip system, please refer to the schematic diagram of the structure of the chip 10200 shown in Figure 10B, but it is not limited thereto.

[0495] Chip 10200 includes one or more processors 10201. Chip 10200 is used to perform any of the above methods.

[0496] In some embodiments, chip 10200 further includes one or more interface circuits 10202. Optionally, terms such as interface circuit, interface, and transceiver pin can be used interchangeably. In some embodiments, chip 10200 further includes one or more memories 10203 for storing data. Optionally, all or part of the memories 10203 may be located outside of chip 10200. Optionally, interface circuit 10202 is connected to memory 10203, and interface circuit 10202 can be used to receive data from memory 10203 or other devices, and interface circuit 10202 can be used to send data to memory 10203 or other devices. For example, interface circuit 10202 can read data stored in memory 10203 and send the data to processor 10201.

[0497] In some embodiments, the interface circuit 10202 performs at least one of the communication steps such as sending and / or receiving in the above method (e.g., steps S3101, S3102, S3104, S3106, S3107, S3109, S3110, S3112, S3113, S3201, S3202, S3204, S3206, S3207, S3209, S3210, S3212, S3213, but not limited thereto). For example, the interface circuit 10202 performing the communication steps such as sending and / or receiving in the above method means that the interface circuit 10202 performs data interaction between the processor 10201, the chip 10200, the memory 10203, or the transceiver device. In some embodiments, the processor 10201 performs at least one of other steps (e.g., steps S3103, S3105, S3108, S3111, S3203, S3205, S3208, S3211, but not limited thereto).

[0498] 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.

[0499] This disclosure also proposes a storage medium storing instructions that, when executed on a communication device 10100, cause the communication device 10100 to perform any of the methods described above. Optionally, the storage medium is an electronic storage medium. Optionally, the storage medium is a computer-readable storage medium, but is 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 is not limited thereto; it may also be a temporary storage medium.

[0500] This disclosure also proposes a program product that, when executed by the communication device 10100, causes the communication device 10100 to perform any of the above methods. Optionally, the program product is a computer program product.

[0501] This disclosure also proposes a computer program that, when run on a computer, causes the computer to perform any of the above methods.

[0502] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0503] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A communication method, executed by a terminal, wherein, The method includes: The terminal receives a first message sent by a first network element, wherein the first message carries first information, and the first information is used to configure the next-hop link count (NCC) for the terminal.

2. The method according to claim 1, wherein, The NCC is used to implement the Layer 1 / 2 triggered mobility LTM handover of the terminal.

3. The method according to claim 1 or 2, wherein, The first network element includes at least one of the following: Core network equipment; Access network equipment.

4. The method according to any one of claims 1 to 3, wherein, The first message includes at least one of the following: Non-access stratum NAS messages; Radio Resource Control (RRC) configuration message.

5. The method according to any one of claims 1 to 4, wherein, The first information includes at least one of the following: Initial NCC value; Updated NCC value.

6. The method according to claim 5, wherein, The initial NCC value is determined by the access network equipment.

7. The method according to any one of claims 3 to 6, wherein, The first information is that the terminal is configured with NCC to satisfy at least one of the following: The initial NCC value is configured by the access network device via RRC configuration messages; The updated NCC value is configured by the core network device via NAS messages; The updated NCC value is configured by the access network device via RRC configuration messages.

8. The method according to any one of claims 1 to 7, wherein, The method further includes: The terminal receives a second message sent by an access network device, wherein the second message is used to instruct the terminal to switch to another access network device.

9. The method according to claim 8, wherein, The second message includes a first indication message, which is used to indicate the key update type to the terminal.

10. The method according to claim 9, wherein, The key update type includes at least one of the following: By K AMF Update; By K gNB Update; Updated by the next hop NH.

11. The method according to any one of claims 8 to 10, wherein, The method further includes: Determine the key update type; Perform key update synchronization based on the NCC according to the key update type.

12. A communication method, executed by a core network device, wherein, The method includes: Send a first message to the terminal, wherein the first message carries first information, the first information being used to configure the next-hop link count (NCC) for the terminal.

13. The method according to claim 12, wherein, The NCC is used to implement the Layer 1 / 2 triggered mobility LTM handover of the terminal.

14. The method according to claim 12 or 13, wherein, The first message is a non-access stratum (NAS) message.

15. The method according to any one of claims 12 to 14, wherein, The first information includes the updated NCC value.

16. The method according to any one of claims 12 to 15, wherein, The method further includes: Receive a third message sent by the access network device, wherein the third message is used to request N2 path switching; A fourth message is sent to the access network device, wherein the fourth message is used to confirm that the N2 path handover has been completed.

17. The method according to claim 15, wherein, The fourth message includes at least one of the following: Updated NCC value; The next hop NH value corresponds to the updated NCC value.

18. The method according to claim 16 or 17, wherein, The third message includes a second instruction, which instructs the access network device to perform an LTM handover.

19. A communication method, performed by an access network device, wherein, The method includes: Send a first message to the terminal, wherein the first message carries first information, the first information being used to configure the next-hop link count (NCC) for the terminal.

20. The method according to claim 19, wherein, The NCC is used to implement the Layer 1 / 2 triggered mobility LTM handover of the terminal.

21. The method according to claim 19 or 20, wherein, The first message is a Radio Resource Control (RRC) configuration message.

22. The method according to any one of claims 19 to 21, wherein, The first information includes at least one of the following: Initial NCC value; Updated NCC value.

23. The method according to claim 22, wherein, The initial NCC value is determined by the access network device, and the updated NCC value is obtained by the access network device from the core network device.

24. The method according to any one of claims 21 to 23, wherein, The first information is that the terminal is configured with NCC to satisfy at least one of the following: The initial NCC value is configured by the access network device via RRC configuration messages; The updated NCC value is configured by the access network device via RRC configuration messages.

25. The method according to any one of claims 19 to 24, wherein, The method further includes: Determine whether to trigger LTM handover for the terminal; A second message is sent to the terminal, wherein the second message is used to instruct the terminal to switch to another access network device.

26. The method of claim 25, wherein, The second message includes a first indication message, which is used to indicate the key update type to the terminal.

27. The method according to claim 26, wherein, The key update type includes at least one of the following: By K AMF Update; By K gNB Update; Updated by the next hop NH.

28. The method according to any one of claims 19 to 27, wherein, The method further includes: Send a third message to the core network equipment, wherein the third message is used for N2 path switching; The system receives a fourth message from the core network device, wherein the fourth message is used to determine that the N2 path handover has been completed.

29. The method according to claim 28, wherein, The fourth message includes at least one of the following: Updated NCC value; The NH value corresponds to the updated NCC value.

30. The method according to claim 28 or 29, wherein, The third message includes a second instruction, which instructs the access network device to perform an LTM handover.

31. A communication device, disposed in a terminal, wherein, The device includes: The transceiver module is configured to receive a first message sent by a first network element, wherein the first message carries first information, and the first information is used to configure the next-hop link count (NCC) for the terminal.

32. A communication device, disposed in core network equipment, wherein, The device includes: The transceiver module is configured to send a first message to the terminal, wherein the first message carries first information, and the first information is used to configure the next-hop link count (NCC) for the terminal.

33. A communication device, disposed in an access network device, wherein, The device includes: The transceiver module is configured to send a first message to the terminal, wherein the first message carries first information, and the first information is used to configure the next-hop link count (NCC) for the terminal.

34. A communication device, comprising: One or more processors; A memory that stores instructions; When the instruction is executed by the communication device, it causes the communication device to perform at least one of the following: The method as described in any one of claims 1 to 11; The method as described in any one of claims 12 to 18; The method as described in any one of claims 19 to 30.

35. A communication system comprising at least one of the following: a terminal, a core network device, and an access network device; in, The terminal is used to implement the method as described in any one of claims 1 to 11; The core network equipment is used to implement the method as described in any one of claims 12 to 18; The access network device is used to implement the method as described in any one of claims 19 to 30.

36. A storage medium storing instructions, wherein, When the instruction is executed on the communication device, the communication device performs at least one of the following: The method as described in any one of claims 1 to 11; The method as described in any one of claims 12 to 18; The method as described in any one of claims 19 to 30.

37. A computer program product comprising instructions, wherein, when the instructions are executed on a communication device, the communication device performs at least one of the following: The method as described in any one of claims 1 to 11; The method as described in any one of claims 12 to 18; The method as described in any one of claims 19 to 30.

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