Communication method, terminal, access network device, communication system, computer program product and storage medium

Abstract

Embodiments of the present disclosure provide a communication method, a terminal, an access network device, a communication system, a computer program product and a storage medium. The method comprises: determining a key for a radio resource control (RRC) connection reestablishment procedure, wherein the key is used for encryption and / or integrity protection of a message MSG4. The technical solution provided in the embodiments of the present disclosure can make network communication more secure.

Description

Communication method, terminal, access network device, communication system, computer program product and storage medium TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of communication, and in particular to a communication method, a terminal, an access network device, a communication system, a computer program product and a storage medium. BACKGROUND

[0002] In the technical field of communication, with the evolution of communication networks, network communication needs to be more secure, and the security requirements for radio resource control (RRC) connection reestablishment are increasing, for example, it is required to achieve the same high-level security level as RRC connection recovery.

[0003] SUMMARY

[0004] To make network communication more secure.

[0005] According to a first aspect of the embodiments of the present disclosure, the embodiments of the present disclosure provide a communication method, the method is executed by a terminal, and the method comprises:

[0006] determining a key for a radio resource control (RRC) connection reestablishment procedure;

[0007] The key is used for encryption and / or integrity protection of a message MSG4.

[0008] According to a second aspect of the embodiments of the present disclosure, a communication method is provided, the method is executed by an access network device, and the method comprises:

[0009] sending first information to a terminal;

[0010] The first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

[0011] According to a third aspect of the embodiments of the present disclosure, a communication method is provided, the method comprises:

[0012] a network device sends first information to a terminal;

[0013] The first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

[0014] According to a fourth aspect of the embodiments of the present disclosure, a terminal is provided, the terminal comprises:

[0015] a transceiver module configured to:

[0016] Determine a key for use in a radio resource control (RRC) connection reestablishment procedure;

[0017] The key is used for encryption and / or integrity protection of a message MSG4.

[0018] According to a fifth aspect of the embodiments of the present disclosure, an access network device is provided, and the access network device comprises:

[0019] The transceiver is configured to:

[0020] send first information to the terminal;

[0021] The first information is used to indicate a derivation manner of a key, and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

[0022] According to a sixth aspect of the embodiments of the present disclosure, a communication system is provided, and the communication system comprises a terminal and an access network device; the terminal is configured to implement the method of the first aspect, and the access network device is configured to implement the method of the second aspect.

[0023] According to a seventh aspect of the embodiments of the present disclosure, a terminal is provided, and the terminal comprises:

[0024] one or more processors;

[0025] The terminal is configured to implement the method of the first aspect.

[0026] According to an eighth aspect of the embodiments of the present disclosure, an access network device is provided, and the access network device comprises:

[0027] one or more processors;

[0028] The access network device is configured to implement the method of the second aspect.

[0029] According to a ninth aspect of the embodiments of the present disclosure, a computer program product is provided, and the computer program product comprises a computer program or instructions, and the computer program or instructions are executed by a processor to implement the steps of the method of the first aspect and / or the second aspect.

[0030] According to a tenth aspect of the embodiments of the present disclosure, a storage medium is provided, and the storage medium stores instructions, and when the instructions are run on a communication device, the communication device is caused to perform the method provided by the first aspect and / or the second aspect.

[0031] The technical solutions provided by the embodiments of the present disclosure can improve the security of network communication.

[0032] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the embodiments of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following describes the drawings required by the embodiments, and the following drawings are only some embodiments of the present disclosure, and do not specifically limit the protection scope of the present disclosure.

[0034] FIG. 1a is a schematic diagram of a communication system architecture according to an example embodiment;

[0035] FIG. 1b is a schematic diagram of a communication method according to an example embodiment;

[0036] FIG. 1c is a schematic diagram of a communication method according to an example embodiment;

[0037] FIG. 1d is a schematic diagram of a communication method according to an example embodiment;

[0038] FIG. 1e is a schematic diagram of a communication method according to an example embodiment;

[0039] FIG. 1f is a schematic diagram of a communication method according to an example embodiment;

[0040] FIG. 1g is a schematic diagram of a communication method according to an example embodiment;

[0041] FIG. 1h is a schematic diagram of a communication method according to an example embodiment;

[0042] FIG. 2a is a schematic diagram of a communication method flow according to an example embodiment;

[0043] FIG. 3a is a schematic diagram of a communication method flow according to an example embodiment;

[0044] FIG. 3b is a schematic diagram of a communication method flow according to an example embodiment;

[0045] FIG. 4a is a schematic diagram of a communication method flow according to an example embodiment;

[0046] FIG. 4b is a schematic diagram of a communication method flow according to an example embodiment;

[0047] FIG. 5a is a schematic diagram of a communication method flow according to an example embodiment;

[0048] FIG. 6a is a schematic diagram of a structure of a first device according to an example embodiment;

[0049] FIG. 6b is a structural schematic diagram of a second device, according to an example embodiment;

[0050] FIG. 7a is a structural schematic diagram of a UE, according to an example embodiment;

[0051] FIG. 7b is a structural schematic diagram of a communication device, according to an example embodiment. DETAILED DESCRIPTION

[0052] Embodiments of the present disclosure provide a communication method, a terminal, an access network device, a communication system, a computer program product and a storage medium.

[0053] In a first aspect, embodiments of the present disclosure provide a communication method, the method being performed by a terminal, the method comprising:

[0054] determining a key for a radio resource control (RRC) connection reestablishment procedure;

[0055] wherein the key is used for encryption and / or integrity protection of a message (MSG4).

[0056] In the above embodiment, after determining the key for encryption and / or integrity protection of the MSG4 for the RRC reestablishment procedure, an operation corresponding to the encryption and / or integrity protection of the MSG4 can be performed based on the key, so that the transmission of the MSG4 is more secure and reliable.

[0057] In some embodiments in combination with the first aspect, the method further comprises:

[0058] determining a derivation manner of the key;

[0059] wherein the derivation manner is one of:

[0060] a horizontal derivation manner;

[0061] a vertical derivation manner.

[0062] In the above embodiment, the derivation manner of the key can be determined explicitly.

[0063] In some embodiments in combination with the first aspect, the determination of the derivation manner of the key comprises:

[0064] determining the derivation manner of the key by at least one of:

[0065] a handover type;

[0066] received first information.

[0067] In the above embodiments, the terminal can determine the derivation manner of the key in different ways, and the method of determining the derivation manner is more flexible.

[0068] In some embodiments of the first aspect, in some embodiments, the determining the derivation manner of the key based on the received first information comprises any one of the following:

[0069] In a case where the first information indicates the vertical derivation manner, determining the derivation manner of the key as the vertical derivation manner;

[0070] In a case where the first information indicates the horizontal derivation manner, determining the derivation manner of the key as the horizontal derivation manner;

[0071] In a case where the first information is not received, determining the derivation manner of the key as the vertical derivation manner.

[0072] In a case where the first information is not received, determining the derivation manner of the key as the horizontal derivation manner.

[0073] In the above embodiments, the derivation manner of the key can be determined as different derivation manners in different scenarios, and the determination manner is more flexible.

[0074] In some embodiments of the first aspect, in some embodiments, the determining the derivation manner of the key based on the handover type comprises:

[0075] determining the derivation manner of the key based on a handover type indicated by second information;

[0076] The handover type is one of the following:

[0077] A first handover type, the first handover type being an Xn handover;

[0078] A second handover type, the second handover type being an NG handover;

[0079] A third handover type, the third handover type being an intra-gNB handover;

[0080] A fourth handover type, the fourth handover type being an intra-CU handover.

[0081] In the above embodiments, the derivation manner of the key can be determined based on the handover type indicated by the second information, so that the derivation manner can be adapted to the handover type indicated by the second information.

[0082] In some embodiments of the first aspect, in some embodiments, the determining the derivation manner of the key based on the handover type indicated by the second information comprises any one of the following:

[0083] the second information indicates that the switching type of the switching is the first switching type, and the derivation manner of the key is determined as a vertical derivation manner;

[0084] the second information indicates that the switching type of the switching is the second switching type, and the derivation manner of the key is determined as a horizontal derivation manner;

[0085] the second information indicates that the switching type of the switching is the third switching type, and the derivation manner of the key is determined as a horizontal derivation manner;

[0086] the second information indicates that the switching type of the switching is the fourth switching type, and the derivation manner of the key is determined as a horizontal derivation manner.

[0087] In the above embodiment, the derivation manner of the key can be flexibly determined based on the switching type.

[0088] With reference to some embodiments of the first aspect, in some embodiments, the method further includes:

[0089] receiving third information;

[0090] The third information is used to indicate a next hop chaining count NCC used when the RRC connection is reestablished.

[0091] In the above embodiment, the terminal can obtain, from the access network device, third information used to indicate a next hop chaining count NCC used when the RRC connection is reestablished.

[0092] With reference to some embodiments of the first aspect, in some embodiments, the method further includes:

[0093] determining that the switching fails and that a next hop variable parameter NH corresponding to the NCC is not used, and generating the NH based on the NCC.

[0094] In the above embodiment, in a case where it is determined that the switching fails and that the NH corresponding to the NCC is not used, the NH can be generated based on the NCC.

[0095] With reference to some embodiments of the first aspect, in some embodiments, the method further includes:

[0096] determining that the switching succeeds and that the NCC indicated by the third information is the same as an NCC configured for the RRC connection reestablishment and that the NH is not used, and generating the NH based on a vertical derivation manner.

[0097] In the above embodiment, in a case where it is determined that the switching succeeds and that the NCC indicated by the third information is the same as an NCC configured for the RRC connection reestablishment and that the NH is not used, the NH can be generated based on the NCC.

[0098] In some embodiments of the first aspect, in some embodiments, the method further comprises:

[0099] receiving fourth information in the RRC connected state;

[0100] The fourth information is used to indicate an inactive state radio network temporary identifier (I-RNTI), and the I-RNTI is used for RRC connection reestablishment and / or RRC connection resume.

[0101] In the above embodiments, in the RRC connected state, the terminal can obtain the fourth information sent by the network device and used to indicate the I-RNTI, so that the terminal can perform RRC connection reestablishment and / or RRC connection resume based on the I-RNTI.

[0102] In some embodiments of the first aspect, in some embodiments, the I-RNTI is an identifier configured for each access network device; or the I-RNTI is an identifier configured for access network devices in a first set, and the first set includes at least two access network devices.

[0103] In the above embodiments, the I-RNTI can be configured in granularity of a single access network device, or the I-RNTI can be configured in granularity of a first set, so that the configuration is more flexible.

[0104] In some embodiments of the first aspect, in some embodiments, the I-RNTI is used to identify context information of the terminal and / or determine an access network device where the context information is located.

[0105] In some embodiments of the first aspect, in some embodiments, the receiving of the fourth information comprises at least one of:

[0106] determining access network device switching, and receiving the fourth information;

[0107] determining intra-central unit (inter-CU) switching, and receiving the fourth information.

[0108] In the above embodiments, the fourth information can be received in a case where access network device switching and / or intra-central unit (inter-CU) switching is determined, so that the way of obtaining the fourth information is more flexible.

[0109] In a second aspect, the embodiments of the present disclosure provide a communication method, the method is performed by an access network device, and the method comprises:

[0110] sending first information to a terminal;

[0111] The first information is used to indicate the method of key derivation; the key is used for encryption and / or integrity protection of message MSG4 in the RRC connection reconstruction process.

[0112] In conjunction with some embodiments of the second aspect, in some embodiments, the derived method is one of the following:

[0113] Horizontal derivation method;

[0114] Vertical derivation method.

[0115] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes:

[0116] Send third information to the terminal;

[0117] The third information is used to indicate the number of next-hop links (NCC) used during RRC connection reconstruction.

[0118] In conjunction with some embodiments of the second aspect, in some embodiments, the method further includes:

[0119] In the RRC connection state, send the fourth information to the terminal;

[0120] The fourth piece of information is used to indicate the inactive wireless network temporary identifier I-RNTI, which is used for RRC connection reconstruction and / or RRC connection recovery.

[0121] In conjunction with some embodiments of the second aspect, in some embodiments, the I-RNTI is an identifier configured for each access network device; or, the I-RNTI is an identifier configured for access network devices in a first set, the first set including at least two access network devices.

[0122] In conjunction with some embodiments of the second aspect, in some embodiments, the I-RNTI is used to identify the context information of the terminal and / or determine the access network device where the context information is located.

[0123] In conjunction with some embodiments of the second aspect, in some embodiments, sending the fourth information to the terminal includes at least one of the following:

[0124] Upon determining the access network device switchover, the fourth piece of information is sent to the terminal;

[0125] The system determines the inter-CU switching within the centralized unit and sends the fourth information to the terminal.

[0126] In conjunction with some embodiments of the second aspect, in some embodiments, the terminal adopts a vertical derivation method, and the method further includes:

[0127] determining that the access network device has an unused next hop parameter NH, and generating the key based on the NH and a vertical derivation manner.

[0128] In some embodiments of the second aspect, the method further comprises:

[0129] determining that the access network device does not have the unused NH, and sending fifth information to a core network device;

[0130] The fifth information is used to request the core network device to configure the NH.

[0131] In some embodiments of the second aspect, the terminal adopts a horizontal derivation manner, and the method further comprises one of the following:

[0132] determining that the access network device has the unused NH, and that a source service access device and a target access network device corresponding to the RRC connection reestablishment are the same access network device, performing an intra-gNB handover and a key isolation operation using the NH after the RRC connection is reestablished;

[0133] determining that the access network device has the unused NH, and discarding the NH.

[0134] In a third aspect, the embodiments of the present disclosure provide a communication method, and the method comprises:

[0135] a network device sends first information to a terminal;

[0136] The first information is used to indicate a derivation manner of a key, and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment process.

[0137] In a fourth aspect, the embodiments of the present disclosure provide a terminal, and the terminal comprises:

[0138] a transceiver module configured to:

[0139] determine a key for an RRC connection reestablishment process;

[0140] The key is used for encryption and / or integrity protection of a message MSG4.

[0141] In a fifth aspect, the embodiments of the present disclosure provide an access network device, and the access network device comprises:

[0142] a transceiver module configured to:

[0143] send first information to a terminal;

[0144] The first information is used to indicate a derivation manner of a key, and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

[0145] In a sixth aspect, the embodiments of the present disclosure provide a communication system including a terminal and an access network device; the terminal is configured to implement the method in the first aspect, and the access network device is configured to implement the method in the second aspect.

[0146] In a seventh aspect, the embodiments of the present disclosure provide a terminal, which includes:

[0147] one or more processors;

[0148] The terminal is configured to implement the method in the first aspect.

[0149] In an eighth aspect, the embodiments of the present disclosure provide an access network device, which includes:

[0150] one or more processors;

[0151] The access network device is configured to implement the method in the second aspect.

[0152] In a ninth aspect, the embodiments of the present disclosure provide a storage medium, which stores instructions, when the instructions are executed on a communication device, the communication device is caused to implement the method described in the optional implementation manner of the first aspect and / or the second aspect.

[0153] In a tenth aspect, the embodiments of the present disclosure provide a program product, when the program product is executed on a communication device, the communication device is caused to implement the method described in the optional implementation manner of the first aspect and / or the second aspect.

[0154] In an eleventh aspect, the embodiments of the present disclosure provide a computer program, when the computer program is executed on a computer, the computer is caused to implement the method described in the optional implementation manner of the first aspect and / or the second aspect.

[0155] In a twelfth aspect, the embodiments of the present disclosure provide a chip or chip system. The chip or chip system includes processing circuitry configured to implement the method described in the above-mentioned first aspect and / or the optional implementation manner of the second aspect.

[0156] It can be understood that the above-mentioned terminal, access network device, communication system, storage medium, program product, computer program, chip or chip system are all used to implement the method proposed in the embodiments of the present disclosure. Therefore, the beneficial effects that can be achieved are referred to the beneficial effects in the corresponding method, which will not be described here.

[0157] The embodiments of the present disclosure provide a communication method, a terminal, an access network device, a communication system and a storage medium. In some embodiments, the communication method and the information indication method, information processing method, information transmission method and the like can be replaced with each other, and the communication system and the information processing system can be replaced with each other.

[0158] The embodiments of the present disclosure are not exhaustive, but only illustrate some embodiments, and are not specific limitations on the protection scope of the present disclosure. In the case of no contradiction, each step in an embodiment can be implemented as an independent embodiment, and the steps can be combined arbitrarily, for example, the scheme after removing some steps in an embodiment can also be implemented as an independent embodiment, and the order of the steps in an embodiment can be exchanged arbitrarily, in addition, the optional implementation manners in an embodiment can be combined arbitrarily; in addition, the embodiments can be combined arbitrarily, for example, some or all steps of different embodiments can be combined arbitrarily, an embodiment can be combined with the optional implementation manners of other embodiments.

[0159] In each embodiment of the present disclosure, the terms and / or descriptions between the embodiments are consistent if there is no special description and logical conflict, and can be referred to each other, and the technical features in different embodiments can be combined to form a new embodiment according to their inherent logical relationship.

[0160] The terms used in the embodiments of the present disclosure are only for the purpose of describing the specific embodiments, and not as a limitation on the present disclosure.

[0161] In the embodiments of the present disclosure, unless otherwise specified, the elements expressed in singular form, such as "one", "a", "the", "above", "said", "preceding", "this" and the like, can represent "one and only one", and can also represent "one or more", "at least one" and the like. For example, in the case of using articles such as "a", "an", "the" and the like in English, the noun after the article can be understood as singular expression, and can also be understood as plural expression.

[0162] In the embodiments of the present disclosure, "a plurality of" means two or more.

[0163] In some embodiments, the terms "at least one of", "one or more", "a plurality of", "multiple" and the like can be replaced with each other.

[0164] In some embodiments, "at least one of A, B", "A and / or B", "in one case A, in another case B", "responsive to case A, responsive to case B" and the like, can be interpreted to include both cases, A and B, in some embodiments, A (A is performed regardless of B), in some embodiments, B (B is performed regardless of A), in some embodiments, selected from the group consisting of A and B (the selection between A and B is an option), in some embodiments, A and B (both A and B are performed).

[0165] In some embodiments, "A or B" and the like, can be interpreted to include both cases, A and B, in some embodiments, A (A is performed regardless of B), in some embodiments, B (B is performed regardless of A), in some embodiments, selected from the group consisting of A and B (the selection between A and B is an option).

[0166] In some embodiments, the prefix words "first", "second" and the like in the disclosure do not limit the position, order, priority, number or content of the described objects, and the description of the described objects should be understood in the context of the claims or embodiments, and should not be construed as redundant limitations. For example, the described object is "field", and the ordinal words before "field" in "first field" and "second field" do not limit the position or order between "fields", and "first" and "second" do not limit whether the "fields" modified by them are in the same message or not, nor do they limit the order of "first field" and "second field". For another example, the described object is "level", and the ordinal words before "level" in "first level" and "second level" do not limit the priority between "levels". For another example, the number of described objects is not limited by ordinal words, and can be one or more. For example, "first device", where the number of "devices" can be one or more. In addition, objects modified by different prefix words can be the same or different, for example, the described object is "device", and "first device" and "second device" can be the same device or different devices, and their types can be the same or different; for another example, the described object is "information", and "first information" and "second information" can be the same information or different information, and their contents can be the same or different.

[0167] In some embodiments, "including A", "containing A", "for indicating A", "carrying A" can be interpreted as directly carrying A, or indirectly indicating A.

[0168] In some embodiments, the terms "in response to", "in response to determining", "in the case of", "when", "when", "if", "if" and the like can be replaced with each other.

[0169] 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", "above", and the like can be replaced with each other, and the terms "less than", "less than or equal to", "not greater than", "fewer than", "fewer than or equal to", "not more than", "lower than", "lower than or equal to", "not higher than", "below", and the like can be replaced with each other.

[0170] In some embodiments, the apparatuses and devices can be interpreted as physical or virtual, and their names are not limited to the names described in the embodiments, and in some cases can also be understood as "equipment", "device", "circuit", "network element", "node", "function", "unit", "section", "system", "network", "chip", "chip system", "entity", "subject", and the like.

[0171] In some embodiments, "network" can be interpreted as an apparatus included in the network, such as an access network device, a core network device, and the like.

[0172] In some embodiments, an “access network device (AN device)” can also be referred to as a “radio access network device (RAN device),” a “base station (BS),” a “radio base station,” a “fixed station,” and in some embodiments can also be understood as a “node,” an “access point,” a “transmission point (TP),” a “reception point (RP),” a “transmission / reception point (TRP),” a “panel,” an “antenna panel,” an “antenna array,” a “cell,” a “macro cell,” a “small cell,” a “femto cell,” a “pico cell,” a “sector,” a “cell group,” a “serving cell,” a “carrier,” a “component carrier,” a “bandwidth part (BWP),” and the like.

[0173] In some embodiments, a "terminal" or "terminal device" can be referred to as a "user equipment" (UE), a "user terminal," a "mobile station" (MS), a "mobile terminal" (MT), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, and / or the like.

[0174] In some embodiments, data, information, and / or the like can be obtained in compliance with laws and regulations of a country in which data is obtained.

[0175] In some embodiments, data, information, and / or the like can be obtained after obtaining consent of a user.

[0176] In addition, each element, each row, or each column in a table of embodiments of the present disclosure can be implemented as an independent embodiment, and a combination of any element, any row, or any column can also be implemented as an independent embodiment.

[0177] FIG. 1a is a schematic diagram of an architecture of a communication system according to embodiments of the present disclosure.

[0178] As shown in FIG. 1a, a communication system 100 includes a terminal 101 and a network device 102.

[0179] In some embodiments, the network device 102 can include at least one of an access network device 1021 and a core network device 1022.

[0180] In some embodiments, the terminal includes at least one of a mobile phone, a wearable device, an Internet of Things device, a communication-capable automobile, a smart automobile, a tablet (Pad), a wireless transceiver-equipped computer, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in industrial control, a wireless terminal device in self-driving, a wireless terminal device in remote medical surgery, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, a wireless terminal device in a smart home, and the like, but is not limited thereto.

[0181] In some embodiments, the access network device can be at least one of a node or a device that accesses a terminal to a wireless network, and can include an evolved NodeB (eNB) in a 5G communication system, a next generation eNB (ng-eNB), a next generation NodeB (gNB), a node B (NB), a home node B (HNB), a home evolved node B (HeNB), a wireless backhaul device, a radio network controller (RNC), a base station controller (BSC), a base transceiver station (BTS), a base band unit (BBU), a mobile switching center, a base station in a 6G communication system, an Open RAN, a Cloud RAN, a base station in other communication systems, an access node in a Wi-Fi system, and the like, but is not limited thereto.

[0182] In some embodiments, the technical solutions of the present disclosure can be applied to an Open RAN architecture, in which case, the interfaces between or within the access network devices involved in the embodiments of the present disclosure can become internal interfaces of the Open RAN, and the processes and information interactions between these internal interfaces can be implemented through software or programs.

[0183] In some embodiments, the access network device can be composed of a central unit (CU) and a distributed unit (DU), where the CU can also be referred to as a control unit. The CU-DU structure can split the protocol layers of the access network device, with some of the protocol layers being controlled by the CU and the rest of the protocol layers or all of the protocol layers being distributed in the DUs and controlled by the CU, but is not limited thereto.

[0184] In some embodiments, the core network device can be one device including one or more network elements, or can be multiple devices or device groups including all or part of the one or more network elements. The network element can be virtual or physical. The core network includes at least one of an evolved packet core (EPC), a 5G core network (5GCN), and a next-generation core (NGC).

[0185] It can be understood that the communication system described in the embodiments of the present disclosure is for more clearly illustrating the technical solutions of the embodiments of the present disclosure, and does not constitute a limitation on the technical solutions provided by the embodiments of the present disclosure. Those skilled in the art can know that, as the system architecture evolves and new business scenarios appear, the technical solutions provided by the embodiments of the present disclosure are also applicable to similar technical problems.

[0186] The following embodiments of the present disclosure can be applied to the communication system 100 shown in FIG. 1a or part of the subject, but are not limited thereto. The subjects shown in FIG. 1a are exemplary, and the communication system can include all or part of the subjects in FIG. 1a, or can include other subjects other than those in FIG. 1a. The number and form of each subject is arbitrary, and the connection relationship between the subjects is exemplary. The subjects can be connected or not connected, and the connection can be in any manner, can be direct connection or indirect connection, and can be wired connection or wireless connection.

[0187] Embodiments of the present disclosure can be applied to Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 5G new radio (NR), Future Radio Access (FRA), New-Radio Access Technology (RAT), New Radio (NR), New radio access (NX), Future generation radio access (FX), Global System for Mobile communications (GSM (registered trademark)), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (Bluetooth (registered trademark)), Public Land Mobile Network (PLMN) network, Device-to-Device (D2D) system, Machine to Machine (M2M) system, Internet of Things (IoT) system, Vehicle-to-Everything (V2X), system using other communication methods, next-generation system expanded based on them, and the like. In addition, a plurality of systems can be combined (for example, combination of LTE or LTE-A and 5G, and the like).

[0188] In some embodiments, a trigger cause of a radio resource control (RRC) connection reestablishment in new radio (NR) can be when in an RRC connected state but a handover failure, a radio link failure, an integrity protection failure, an RRC reconfiguration failure, or the like occurs, the procedure is triggered.

[0189] In some embodiments, the application premise of RRC connection reestablishment is that the access stratum (AS) security activation has been activated, and the signaling radio bearer (SRB2) and data radio bearer (DRB) are established.

[0190] In some embodiments, in order to perform cell selection for RRC connection reestablishment, start timer T311, T311 timeout, or reselect to inter-RAT cell (inter-radio access technology cell), the UE returns to idle state.

[0191] In some embodiments, the UE sends the RRC connection reestablishment request on SRB0 through the uplink common control channel (CCCH, Common Control Channel), carrying the UE's AS layer initial identification information, the truncated integrity protection message verification code (ShortMAC-I, Short Message Authentication Code-Integrity) and the reestablishment reason, which corresponds to Msg3 of the random access process. Before the UE sends the message, it restores SRB1 and uses the SRB1 default configuration to wait for MSG4.

[0192] In some embodiments, the base station (gNB) replies (different from LTE, which replies on SRB0) the RRC connection reestablishment message (RRCReestablilshment) on SRB1 through the downlink dedicated control channel (DCCH, Dedicated Control Channel), which corresponds to Msg4 of the random access process, does not carry any radio resource configuration information (except next hop chaining count (NCC)), and MSG4 is integrity protected but not encrypted. After the UE receives MSG4, it updates the key according to NCC and integrity protection verifies MSG4.

[0193] In some embodiments, the UE sends the RRC connection reestablishment complete RRCReestablilshmentComplete message on SRB1 through the uplink DCCH, which does not carry any information and serves as an RRC layer confirmation function, and MSG5 is encrypted and integrity protected.

[0194] In some embodiments, the reason for RRC connection reestablishment failure can be that the RRC connection reestablishment request timer T301 times out, or the selected cell is not suitable, or the RRC connection reestablishment message (MSG4) integrity protection verification fails.

[0195] In some embodiments, if the RRC connection re-establishment fails, the UE goes back to RRC_IDLE state.

[0196] In some embodiments, if there is no UE context information in the gNB, a RRC connection setup message is replied on SRB0 through downlink CCCH. After receiving this message, the UE deletes the previous context and performs the RRC connection setup procedure.

[0197] It should be noted that, unlike LTE, there is no RRCReject message for RRC connection re-establishment.

[0198] Please refer to FIG. 1b and FIG. 1c, FIG. 1b shows a schematic diagram of RRC connection re-establishment, and FIG. 1c shows a schematic diagram of RRC setup.

[0199] In some embodiments, for the UE in RRC INACTIVE state, when there is uplink data, or the periodic RAN notification area (RNA) update (RNAU) timer expires, or the initial RAN paging is received, etc., this procedure is triggered.

[0200] For RRC connection resumption to RRC connected state:

[0201] In some embodiments, the UE sends the RRC connection resumption request on SRB0 through uplink CCCH, carrying the UE's AS layer initial identification information, ShortMAC-I and resumption reason, which corresponds to the Msg3 of the random access procedure. After sending the message, the UE activates security and generates a key, and resumes SRB1 to wait for MSG4.

[0202] In some embodiments, the gNB replies the RRC connection resumption message on SRB1 through downlink DCCH, which corresponds to the Msg4 of the random access procedure. The MSG4 is encrypted and integrity protected.

[0203] In some embodiments, the UE sends the RRC connection resumption complete message on SRB1 through uplink DCCH, which does not carry any actual information, and only serves as the function of RRC layer confirmation.

[0204] For RRC connection resumption to RRC inactive state:

[0205] In some embodiments, if the gNB decides to release the UE to RRC INACTIVE state (e.g. periodic RNAU) after receiving the RRC Connection Resume Request message, the base station MSG4 message carries a RRC Connection Release RRCRelease message which updates the INACTIVE configuration parameters.

[0206] For RRC Connection Resume to RRC IDLE state:

[0207] In some embodiments, if the gNB decides to release the UE to RRC IDLE state after receiving the RRC Connection Resume Request message, the base station MSG4 message carries a RRC Release message.

[0208] In some embodiments, RRC Connection Resume failure can be RRC Connection Resume Request timer T319 expiry, RRC Connection Resume message (MSG4) integrity protection verification failure or cell reselection occurs during T310 running.

[0209] In some embodiments, RRC Connection Reestablishment failure, the UE goes back to RRC IDLE state.

[0210] In some embodiments, if the gNB does not have the UE's context information, it replies with a RRC Connection Reestablishment message on SRB0 over DL CCCH. Upon receiving this message, the UE deletes the previous context and performs the RRC Connection Setup procedure.

[0211] In some embodiments, RRC Reject message is received, e.g. network load control reason. At this time the UE goes back to the initial RRC INACTIVE state.

[0212] See Figure Id, which shows a diagram of RRC Connection Resume Request and Release; see Figure 1e, which shows a diagram of RRC Connection Resume Request and Release; see Figure 1g, which shows a diagram of RRC Connection Resume Request, Resume and Completion; see Figure 1g, which shows a diagram of RRC Connection Resume Request, RRC Setup and Completion; see Figure 1h, which shows a diagram of RRC Connection Resume Request and Rejection.

[0213] In some embodiments, RRC Connection Reestablishment and RRC Connection Resume have a common feature that is to resume RRC connection and traffic based on the context existing on the network side.

[0214] In some embodiments, the RRC connection reestablishment procedure focuses on restoring the RRC connection, and an RRC connection reconfiguration message is needed to configure the bearers. The RRC connection resume procedure focuses on restoring the RRC connection and the service bearers; therefore, the RRC connection resume procedure has a shorter latency. At the same time, the RRC connection resume procedure has better security.

[0215] In some embodiments, the RRC connection reestablishment and the RRC connection resume are based on a unified model. A unified signaling architecture is adopted to improve the security in the RRC connection reestablishment procedure and reduce the service interruption latency.

[0216] In some embodiments, since the RRC connection reestablishment and the RRC connection resume are two independent procedures, the UE needs to implement two features when implementing them, but the two features are relatively similar.

[0217] In some embodiments, in the process of evolution from 4G to 5G, the security requirements are gradually strengthened and strict, and in the 6G era, the security of the RRC connection reestablishment can be more strict, reaching the same security level as the RRC connection resume, that is, the MSG4 (RRC connection reestablishment) message can be encrypted and integrity protected, which can reduce the RRC reestablishment latency, reduce the service interruption latency, and improve the user experience.

[0218] FIG. 2a is an interaction schematic diagram of a communication method according to an embodiment of the present disclosure. As shown in FIG. 2a, the embodiment of the present disclosure relates to a communication method, for a communication system 100, the method comprising:

[0219] Step S2101: The access network device sends fourth information to the terminal.

[0220] In some embodiments, the terminal receives the fourth information sent by the access network device.

[0221] In some embodiments, the terminal receives the fourth information sent by the access network device in the RRC connected state. Of course, the terminal can also obtain the fourth information from other subjects other than the access network device, which is not limited here. It should be noted that the RRC connected state can also be understood as the terminal being in the RRC connected state, which is not limited here.

[0222] In some embodiments, the access network device sends the fourth information to the terminal after determining the access network device switching.

[0223] In some embodiments, the access network device sends the fourth information to the terminal after determining the inter-CU (inter Centralized Unit) switching.

[0224] It should be noted that the access network device switching or inter-CU switching can be caused or resulted from terminal movement.

[0225] In some embodiments, the fourth information is used to indicate an Inactive Radio Network Temporary Identifier (I-RNTI).

[0226] It should be noted that the fourth information sent by the access network device to the terminal in the case of access network device switching or inter-CU switching can be an I-RNTI used to update the initial configuration. Illustratively, the I-RNTI is used to update the initial configuration only when the access network device switching or inter-CU switching occurs.

[0227] In some embodiments, the I-RNTI is used for RRC connection reestablishment and / or RRC connection resume.

[0228] In some embodiments, the I-RNTI is used in both RRC connection reestablishment and RRC connection resume procedures.

[0229] In some embodiments, the I-RNTI is an identifier configured per access network device. For example, an identifier configured per gNB.

[0230] In some embodiments, the I-RNTI is an identifier configured per access network device in a first set. For example, an identifier configured per gNB pool, each pool containing at least one gNB.

[0231] In some embodiments, the first set includes at least two access network devices.

[0232] In some embodiments, the I-RNTI is used to identify context information of the terminal and / or determine an access network device (e.g., a base station) where the context information is located.

[0233] It should be noted that if the access network device is not configured with an I-RNTI, the last serving cell identity and the UE identity of the cell where the terminal is located can be determined based on a physical cell identifier (PCI) and a cell-radio network temporary identifier (C-RNTI) contained in the message MSG3.

[0234] Step S2102: The access network device sends first information to the terminal.

[0235] In some embodiments, the terminal receives first information sent by the access network device.

[0236] In some embodiments, the first information is used to indicate a derivation manner of the key.

[0237] In some embodiments, the key is used for encryption and / or integrity protection of a message MSG4.

[0238] In some embodiments, the derivation manner is one of:

[0239] a horizontal derivation manner;

[0240] a vertical derivation manner.

[0241] In some embodiments, the terminal can generate the key based on a next hop parameter (NH) and the derivation manner.

[0242] It should be noted that if the terminal determines the derivation manner of the key based on a communication protocol rule or a handover type in step S2103, step S2103 is an optional step.

[0243] Step S2103: The terminal determines a derivation manner.

[0244] In some embodiments, the terminal determines a derivation manner of the key.

[0245] In some embodiments, the derivation manner of the key is determined by at least one of:

[0246] a handover type;

[0247] received first information.

[0248] In some embodiments, the terminal can determine the derivation manner based on the received first information.

[0249] For example, if the first information indicates a horizontal derivation manner, the derivation manner is determined to be a horizontal derivation manner; if the first information indicates a vertical derivation manner, the derivation manner is determined to be a vertical derivation manner.

[0250] In some embodiments, in a case where the first information indicates a vertical derivation manner, the derivation manner of the key is determined to be a vertical derivation manner.

[0251] In some embodiments, in a case where the first information indicates a horizontal derivation manner, the derivation manner of the key is determined to be a horizontal derivation manner.

[0252] In some embodiments, in a case where the first information is not received, the derivation manner of the key is determined to be a vertical derivation manner.

[0253] In some embodiments, the derivation manner of the key is determined as a horizontal derivation manner in case that the first information is not received. In some embodiments, the terminal determines the derivation manner of the key based on a communication protocol rule.

[0254] In some embodiments, the determined derivation manner is a horizontal derivation manner or a vertical derivation manner.

[0255] In some embodiments, the derivation manner of the key is determined based on second information.

[0256] In some embodiments, the second information is used to indicate a handover type.

[0257] In some embodiments, the second information is used to indicate a handover type of a last handover.

[0258] In some embodiments, the handover type is one of:

[0259] a first handover type, the first handover type being an Xn handover;

[0260] a second handover type, the second handover type being an NG handover;

[0261] a third handover type, the third handover type being an intra-gNB handover;

[0262] a fourth handover type, the fourth handover type being an intra-CU handover.

[0263] In some embodiments, the second information is a handover command (HO-CMD).

[0264] In some embodiments, the second information indicates that a handover type of a handover is the first handover type, and it is determined that the derivation manner of the key is a vertical derivation manner.

[0265] In some embodiments, the second information indicates that a handover type of a handover is the first handover type, and it is determined that the derivation manner of the key is a horizontal derivation manner.

[0266] In some embodiments, the second information indicates that a handover type of a handover is the second handover type, and it is determined that the derivation manner of the key is a horizontal derivation manner.

[0267] In some embodiments, the second information indicates that a handover type of a handover is the second handover type, and it is determined that the derivation manner of the key is a vertical derivation manner.

[0268] In some embodiments, the second information indicates that the switching type of the switching is the third switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0269] In some embodiments, the second information indicates that the switching type of the switching is the third switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0270] In some embodiments, the second information indicates that the switching type of the switching is the fourth switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0271] In some embodiments, the second information indicates that the switching type of the switching is the fourth switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner. In some embodiments, the second information indicates that the switching type of the last switching is the first switching type, and the terminal determines the derivation manner of the key as the vertical derivation manner.

[0272] In some embodiments, the second information indicates that the switching type of the last switching is the second switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0273] In some embodiments, the second information indicates that the switching type of the last switching is the third switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0274] In some embodiments, the second information indicates that the switching type of the last switching is the fourth switching type, and the terminal determines the derivation manner of the key as the horizontal derivation manner.

[0275] In some embodiments, it is determined that the first information sent by the access network device is not received, and the terminal determines the derivation manner of the key as the horizontal derivation manner, the first information being used to indicate that the derivation manner of the key is the vertical derivation manner.

[0276] In some embodiments, it is determined that the first information sent by the access network device is not received, and the terminal determines the derivation manner of the key as the vertical derivation manner, the first information being used to indicate that the derivation manner of the key is the vertical derivation manner.

[0277] In some embodiments, it is determined that the first information sent by the access network device is not received, and the terminal determines the derivation manner of the key as the vertical derivation manner, the first information being used to indicate that the derivation manner of the key is the horizontal derivation manner.

[0278] In some embodiments, it is determined that the first information sent by the access network device is not received, and the terminal determines the derivation manner of the key as the horizontal derivation manner, the first information being used to indicate that the derivation manner of the key is the horizontal derivation manner.

[0279] Exemplarily, the access network device explicitly indicates the vertical derivation manner through the first information, and if the vertical derivation manner is not explicitly indicated through the first information, the horizontal derivation manner is adopted by default; or, the access network device explicitly indicates the horizontal derivation manner through the first information, and if the horizontal derivation manner is not explicitly indicated through the first information, the vertical derivation manner is adopted.

[0280] Step S2104: The access network device sends third information to the terminal.

[0281] In some embodiments, the terminal receives the third information sent by the access network device.

[0282] In some embodiments, the third information is used to indicate a next hop chaining count NCC used in RRC connection reestablishment.

[0283] In some embodiments, when it is determined that the handover fails and the NH corresponding to the NCC is not used, the terminal generates the NH based on the NCC.

[0284] Exemplarily, the terminal does not generate the NH immediately after obtaining the NCC, but generates the NH based on the NCC when it is determined that the handover fails and the NH corresponding to the NCC is not used.

[0285] In some embodiments, when it is determined that the handover succeeds, it is determined that the NCC indicated by the third information is the same as the NCC configured for RRC connection reestablishment, and the NH is not used, the terminal generates the NH based on the NCC.

[0286] Step S2105: The terminal determines a key.

[0287] In some embodiments, the key used in the radio resource control RRC connection reestablishment procedure is a key generated based on the horizontal derivation manner.

[0288] In some embodiments, the key used in the radio resource control RRC connection reestablishment procedure is a key generated based on the vertical derivation manner.

[0289] In some embodiments, the key used in the radio resource control RRC connection reestablishment procedure is a key generated based on the derivation manner indicated by the first information.

[0290] In some embodiments, the key used in the radio resource control RRC connection reestablishment procedure is a key generated based on the derivation manner determined based on the handover type.

[0291] In some embodiments, the key used in the radio resource control RRC connection reestablishment procedure is a key generated based on the derivation manner determined based on the communication protocol rule.

[0292] In some embodiments, the terminal determines a key used in a radio resource control (RRC) connection reestablishment procedure.

[0293] In some embodiments, the terminal determines the key used in the RRC connection reestablishment procedure as a key generated based on a horizontal derivation manner.

[0294] In some embodiments, the terminal determines the key used in the RRC connection reestablishment procedure as a key generated based on a vertical derivation manner.

[0295] In some embodiments, the terminal determines the key used in the RRC connection reestablishment procedure as a key generated based on a derivation manner indicated by first information.

[0296] In some embodiments, the terminal determines the key used in the RRC connection reestablishment procedure as a key generated based on a derivation manner determined based on a handover type.

[0297] In some embodiments, the terminal determines the key used in the RRC connection reestablishment procedure as a key generated based on a derivation manner determined based on a communication protocol rule.

[0298] Step S2106: The access network device sends fifth information to the core network device.

[0299] In some embodiments, the core network device receives the fifth information sent by the access network device.

[0300] In some embodiments, the fifth information is used to request the core network device to configure the NH.

[0301] In some embodiments, the access network device determines that the access network device has no unused NH, and sends the fifth information to the core network device.

[0302] In some embodiments, the fifth information can be a HO-CMD.

[0303] It should be noted that if the access network device has an unused NH, step S2106 is not necessary.

[0304] In some embodiments, the core network device is an access and mobility management function (AMF).

[0305] Step S2107: The access network device performs an operation.

[0306] In some embodiments, the terminal adopts a vertical derivation manner, and the access network device determines that the access network device has an unused next hop parameter (NH), and generates the key based on the NH and the vertical derivation manner.

[0307] Exemplarily, the terminal adopts the vertical derivation mode by default, and generates the key based on the NH if the access network device has unused NH. If there is no unused NH, the core network device can be requested for the NH.

[0308] In some embodiments, the derivation mode adopted by the terminal is the horizontal derivation mode; it is determined that the access network device has unused NH, and the source service access device and the target access network device corresponding to the RRC connection reestablishment are the same access network device; and the access network device performs intra-gNB switching and key isolation using the NH after reestablishing the RRC connection.

[0309] Exemplarily, the terminal adopts the horizontal derivation mode by default, and performs intra-gNB switching and continues key isolation using the NH after the reestablishment is completed if there is unused NH on the base station side and the original service base station and the reestablished target base station are the same base station.

[0310] In some embodiments, it is determined that the access network device has unused NH, and the access network device discards the NH.

[0311] In some embodiments, the term "information" can be mutually replaced with the terms "message", "signal", "signaling", "report", "configuration", "indication", "instruction", "command", "channel", "parameter", "field", "data", and the like.

[0312] In some embodiments, the term "send" can be mutually replaced with the terms "transmit", "report", "transport", and the like.

[0313] The information indication method related to the embodiments of the present disclosure can include at least one of steps S2101 to S2107. For example, step S2101 can be implemented as an independent embodiment, step S2102 can be implemented as an independent embodiment, step S2103 can be implemented as an independent embodiment, step S2104 can be implemented as an independent embodiment, step S2105 can be implemented as an independent embodiment, step S2106 can be implemented as an independent embodiment, and step S2107 can be implemented as an independent embodiment. For example, step S2103 in combination with step S2104, step S2105, and step S2107 can be implemented as an independent embodiment, step S2101 in combination with step S2103, step S2104, step S2105, and step S2107 can be implemented as an independent embodiment, step S2102 in combination with step S2103, step S2104, step S2105, and step S2107 can be implemented as an independent embodiment, step S2101 in combination with step S2102, step S2103, step S2104, step S2105, and step S2107 can be implemented as an independent embodiment, step S2101 in combination with step S2102, step S2103, step S2104, step S2105, step S2106, and step S2107 can be implemented as an independent embodiment, but the present disclosure is not limited thereto.

[0314] FIG. 3a is a flow diagram illustrating a communication method according to an embodiment of the present disclosure. As shown in FIG. 3a, the embodiments of the present disclosure relate to a communication method, which is performed by a terminal, and the above method includes:

[0315] Step S3101: The terminal receives fourth information sent by the access network device.

[0316] In some embodiments, optional implementation of step S3101 can refer to other associated parts in the embodiments related to step S2101 in FIG. 2a, which will not be described here.

[0317] Step S3102: The terminal receives first information sent by the access network device.

[0318] In some embodiments, optional implementation of step S3102 can refer to other associated parts in the embodiments related to step S2102 in FIG. 2a, which will not be described here.

[0319] Step S3103: The terminal determines a derivation manner.

[0320] In some embodiments, optional implementation of step S3103 can refer to other associated parts in the embodiments related to step S2103 in FIG. 2a, which will not be described here.

[0321] Step S3104: The terminal receives third information sent by the access network device.

[0322] In some embodiments, optional implementation of step S3104 can refer to other associated parts in the embodiments related to step S2104 in FIG. 2a, which will not be repeated here.

[0323] Step S3105: The terminal determines a key.

[0324] In some embodiments, optional implementation of step S3105 can refer to other associated parts in the embodiments related to step S2105 in FIG. 2a, which will not be repeated here.

[0325] The information indication method related to the embodiments of the present disclosure can include at least one of steps S3101 to S3105. For example, step S3101 can be implemented as an independent embodiment, step S3102 can be implemented as an independent embodiment, step S3103 can be implemented as an independent embodiment, step S3104 can be implemented as an independent embodiment, and step S3105 can be implemented as an independent embodiment. For example, step S3103 in combination with step S3104 and step S3105 can be implemented as an independent embodiment, step S3101 in combination with step S3103, step S3104 and step S3105 can be implemented as an independent embodiment, step S3102 in combination with step S3103, step S3104 and step S3105 can be implemented as an independent embodiment, and step S3101 in combination with step S3102, step S3103, step S3104 and step S3105 can be implemented as an independent embodiment, but is not limited thereto.

[0326] FIG. 3b is a flow diagram illustrating a communication method according to an embodiment of the present disclosure. As shown in FIG. 3b, the communication method related to the embodiments of the present disclosure is performed by a terminal, and the above method includes:

[0327] Step S3201: Determine a key for a radio resource control (RRC) connection reestablishment procedure.

[0328] In some embodiments, the key is used for encryption and / or integrity protection of a message MSG4.

[0329] In some embodiments, optional implementation of step S3201 can refer to other associated parts in the embodiments related to step S2105 in FIG. 2a, which will not be repeated here.

[0330] In some embodiments, the method further includes:

[0331] Determining a derivation manner of the key;

[0332] The derivation manner of the key is determined based on the first information.

[0333] a horizontal derivation manner;

[0334] a vertical derivation manner.

[0335] In some embodiments, the determining the derivation manner of the key comprises:

[0336] The derivation manner of the key is determined by at least one of:

[0337] a handover type;

[0338] the received first information.

[0339] In some embodiments, the determining the derivation manner of the key based on the first information comprises any one of:

[0340] in a case where the first information indicates a vertical derivation manner, determining the derivation manner of the key as the vertical derivation manner;

[0341] in a case where the first information indicates a horizontal derivation manner, determining the derivation manner of the key as the horizontal derivation manner;

[0342] in a case where the first information is not received, determining the derivation manner of the key as the vertical derivation manner;

[0343] in a case where the first information is not received, determining the derivation manner of the key as the horizontal derivation manner.

[0344] In some embodiments, the determining the derivation manner of the key based on the handover type comprises:

[0345] determining the derivation manner of the key based on a handover type indicated by second information;

[0346] The handover type is one of:

[0347] a first handover type, the first handover type being an Xn handover;

[0348] a second handover type, the second handover type being an NG handover;

[0349] a third handover type, the third handover type being an intra-gNB handover;

[0350] a fourth handover type, the fourth handover type being an intra-CU handover.

[0351] In some embodiments, the determining the derivation manner of the key based on the handover type indicated by the second information comprises one of:

[0352] the second information indicates that the switching type of the switching is the first switching type, and the derivation manner of the key is determined as a vertical derivation manner;

[0353] the second information indicates that the switching type of the switching is the second switching type, and the derivation manner of the key is determined as a horizontal derivation manner;

[0354] the second information indicates that the switching type of the switching is the third switching type, and the derivation manner of the key is determined as a horizontal derivation manner;

[0355] the second information indicates that the switching type of the switching is the fourth switching type, and the derivation manner of the key is determined as a horizontal derivation manner.

[0356] In some embodiments, the method further includes:

[0357] receiving third information;

[0358] The third information is used to indicate a next hop chaining count NCC used when the RRC connection is reestablished.

[0359] In some embodiments, the method further includes:

[0360] determining that the switching fails and a next hop variable parameter NH corresponding to the NCC is not used, and generating the NH based on the NCC.

[0361] In some embodiments, the method further includes:

[0362] determining that the switching succeeds and the NCC indicated by the third information is the same as an NCC configured for the RRC connection reestablishment and the NH is not used, and generating the NH based on the NCC.

[0363] In some embodiments, the method further includes:

[0364] receiving fourth information when in the RRC connected state;

[0365] The fourth information is used to indicate an inactive state radio network temporary identifier I-RNTI, and the I-RNTI is used for the RRC connection reestablishment and / or the RRC connection recovery.

[0366] In some embodiments, the I-RNTI is an identifier configured for each access network device; or the I-RNTI is an identifier configured for access network devices in a first set, and the first set includes at least two access network devices.

[0367] In some embodiments, the I-RNTI is used to identify context information of the terminal and / or determine an access network device where the context information is located.

[0368] In some embodiments, the receiving the fourth information comprises at least one of:

[0369] determining an access network device switching, and receiving the fourth information;

[0370] determining an inter-CU switching within a centralized unit, and receiving the fourth information.

[0371] FIG. 4a is a flow diagram illustrating a communication method according to an embodiment of the present disclosure. As shown in FIG. 4a, the embodiment of the present disclosure relates to a communication method, which is performed by an access network device, and the above method comprises:

[0372] Step S4101: The access network device sends fourth information to a terminal.

[0373] In some embodiments, the optional implementation of step S4101 can be seen in other associated parts of the embodiments related to step S2101 in FIG. 2a, which will not be repeated here.

[0374] Step S4102: The access network device sends first information to the terminal.

[0375] In some embodiments, the optional implementation of step S4102 can be seen in other associated parts of the embodiments related to step S2102 in FIG. 2a, which will not be repeated here.

[0376] Step S4103: The access network device sends third information to the terminal.

[0377] In some embodiments, the optional implementation of step S4103 can be seen in other associated parts of the embodiments related to step S2104 in FIG. 2a, which will not be repeated here.

[0378] Step S4104: The access network device sends fifth information to a core network device.

[0379] In some embodiments, the optional implementation of step S4104 can be seen in other associated parts of the embodiments related to step S2106 in FIG. 2a, which will not be repeated here.

[0380] Step S4105: The access network device performs an operation.

[0381] In some embodiments, the optional implementation of step S4105 can be seen in other associated parts of the embodiments related to step S2107 in FIG. 2a, which will not be repeated here.

[0382] The information indication method related to the embodiments of the present disclosure can include at least one of steps S4101 to S4105. For example, step S4101 can be implemented as an independent embodiment, step S4102 can be implemented as an independent embodiment, step S4103 can be implemented as an independent embodiment, step S4104 can be implemented as an independent embodiment, and step S4105 can be implemented as an independent embodiment. For example, step S4101 in combination with step S4102, step S4103, and step S4105 can be implemented as an independent embodiment, for example, step S4101 in combination with step S4102, step S4103, step S4104, and step S4105 can be implemented as an independent embodiment, but the present disclosure is not limited thereto.

[0383] FIG. 4b is a flow diagram illustrating a communication method according to an embodiment of the present disclosure. As shown in FIG. 4b, the embodiments of the present disclosure relate to a communication method, which is performed by an access network device, and the above method includes the following steps.

[0384] Step S4201: transmitting first information to a terminal.

[0385] In some embodiments, the first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

[0386] In some embodiments, the optional implementation of step S4201 can refer to other associated parts in the embodiments related to step S2101 in FIG. 2a, which will not be described here.

[0387] In some embodiments, the derivation manner is one of the following:

[0388] horizontal derivation manner;

[0389] vertical derivation manner.

[0390] In some embodiments, the method further includes:

[0391] transmitting third information to the terminal;

[0392] The third information is used to indicate a next hop chaining count NCC used in RRC connection reestablishment.

[0393] In some embodiments, the method further includes:

[0394] transmitting fourth information to the terminal in an RRC connected state;

[0395] The fourth information is used to indicate an inactive radio network temporary identifier I-RNTI, and the I-RNTI is used for RRC connection reestablishment and / or RRC connection recovery.

[0396] In some embodiments, the I-RNTI is an identifier configured for each access network device; or the I-RNTI is an identifier configured for access network devices in a first set, the first set including at least two access network devices.

[0397] In some embodiments, the I-RNTI is used to identify context information of the terminal and / or determine an access network device where the context information is located.

[0398] In some embodiments, the sending of the fourth information to the terminal includes at least one of the following:

[0399] determining an access network device handover, and sending the fourth information to the terminal;

[0400] determining an inter-CU handover within a centralized unit, and sending the fourth information to the terminal.

[0401] In some embodiments, the derivation mode adopted by the terminal is a vertical derivation mode, and the method further includes:

[0402] determining that the access network device has an unused next hop parameter NH, and generating the key based on the NH and the vertical derivation mode.

[0403] In some embodiments, the method further includes:

[0404] determining that the access network device does not have the unused NH, and sending fifth information to a core network device;

[0405] The fifth information is used to request the core network device to configure the NH.

[0406] In some embodiments, the derivation mode adopted by the terminal is a horizontal derivation mode, and the method further includes one of the following:

[0407] determining that the access network device has the unused NH, and that a source serving access device and a target access network device corresponding to the RRC connection reestablishment are the same access network device, performing an intra-gNB handover and a key isolation operation using the NH after reestablishing the RRC connection;

[0408] determining that the access network device has the unused NH, and discarding the NH.

[0409] FIG. 5a is an interaction schematic diagram of a communication method according to an embodiment of the present disclosure. As shown in FIG. 5a, the embodiment of the present disclosure relates to a communication method, which is used in the communication system 100, and the method includes one of the following steps:

[0410] Step S5101: The network device sends first information to the terminal.

[0411] In some embodiments, the first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 of an RRC connection reestablishment procedure.

[0412] The optional implementation of step S5101 can refer to the optional implementation of steps S2101 to S2107 of FIG. 2a and other associated parts in the embodiments involved in FIG. 2a, which will not be repeated here.

[0413] In some embodiments, the above method can include the method of the above-mentioned communication system side, terminal, access network device, and the like, which will not be repeated here.

[0414] In order to better understand the embodiments of the present disclosure, the following will be further described through some exemplary embodiments:

[0415] The purpose of the embodiments of the present disclosure is to adopt a unified procedure for the RRC connection reestablishment procedure and the RRC connection resume procedure, that is, a set of signaling procedures simultaneously supports the RRC connection reestablishment procedure and the RRC connection resume procedure. In this way, the differentiation of UE characteristics is reduced, and the UE implementation is simple. At the same time, the security of the RRC reestablishment procedure is improved, the latency of the RRC reestablishment is reduced, the service interruption latency is reduced, and the user experience is improved.

[0416] In some embodiments, when the UE is in an RRC connected state, the per gNB or per gNB pool I-RNTI is configured, and with mobility, the network side will configure a new I-RNTI when leaving the effective range. Both the RRC connection reestablishment and the RRC connection resume (Resume) use the I-RNTI to identify the context of the terminal and address the base station where the context of the terminal is located. Note that this step is optional. If there is no such configuration, the combination of PCI and C-RNTI in MSG3 is used to represent the last serving cell identity and the UE identity of the UE in the cell. If it is an I-RNTI, it is updated only when the gNB changes or inter-CU handover occurs during the connection state mobility.

[0417] In the RRC connection reestablishment procedure, the key used in MSG4 is a problem to be solved. There is no problem for the UE to generate the key using the horizontal derivation manner and the vertical derivation manner. The key problem is that the UE does not know whether there is an unused NH on the gNB side, because the Xn handover or the NG handover is transparent to the UE. How to align the key between the UE and the gNB side is a problem.

[0418] In some embodiments, whether to adopt vertical derivation or horizontal derivation depends on the judgment of the UE, for example, if it is an Xn handover but no key isolation is experienced, then vertical derivation, otherwise horizontal derivation.

[0419] In some embodiments, the handover command HO-CMD indicates the handover type, for example, indicating whether it is an Xn handover, an NG handover or an intra-gNB handover; if the last handover is an Xn handover, the RRC connection reestablishment adopts vertical derivation of the key, if it is an NG handover or an intra-gNB handover, then the horizontal derivation key is adopted. The derived key is used for encryption and integrity protection of MSG4.

[0420] In some embodiments, the network side indicates the RRC configuration to indicate whether to adopt horizontal derivation or vertical derivation of the key next time if RRC connection reestablishment occurs, for encryption and integrity protection of MSG4.

[0421] In some embodiments, the network side shows the indication of vertical derivation, otherwise the default horizontal derivation. The reverse is also possible.

[0422] In some embodiments, the UE defaults to vertical derivation, if there is an unused NH on the base station side, then vertical derivation, if not, then requests the AMF to configure the NH.

[0423] In some embodiments, the UE defaults to horizontal derivation, if there is an unused NH on the base station side, and the original serving base station and the reestablishment target base station are one base station, then after the reestablishment is completed, intra-gNB handover is performed, and the NH is used to continue key isolation, otherwise the NH is discarded.

[0424] In some embodiments, the base station configures the NCC in the HO-CMD, which is used for the NCC used when reestablishment occurs if failure occurs.

[0425] In some embodiments, after the UE receives the NCC, it does not generate the NH in a hurry, but waits until the handover failure (HO failure) occurs, if the NH corresponding to the NCC is not used. If no failure occurs, the reestablishment process is not involved, but HO occurs, then based on the NCC given in the HO-CMD for handover, if the initially configured NCC is the same as the NCC indicated by the HO-CMD, and the NH is not used, then the vertical derivation mode is triggered to generate the key based on the NH for handover.

[0426] In the embodiments of the present disclosure, part or all of the steps, and optional implementation manners thereof, can be combined with part or all of the steps in other embodiments, or combined with optional implementation manners of other embodiments.

[0427] The embodiments of the present disclosure further provide a device for implementing any of the above methods, for example, a device comprising units or modules for implementing the steps performed by the terminal in any of the above methods. For another example, another device is further provided, comprising units or modules for implementing the steps performed by the network equipment (such as an access network device, a core network function node, a core network device, etc.) in any of the above methods.

[0428] It should be understood that the division of each unit or module in the above device is only a logical function division, and all or part of the units or modules can be integrated into one physical entity or divided on the physical entity in actual implementation. In addition, the units or modules in the device can be implemented in the form of processor invoking software: for example, the device comprises a processor connected with a memory, the memory stores instructions, and the processor invokes the instructions stored in the memory to implement any of the above methods or to implement the functions of the units or modules of the device, wherein the processor is a general processor such as a central processing unit (CPU) or a microprocessor, and the memory is a memory in the device or a memory outside the device. Alternatively, the units or modules in the device can be implemented in the form of hardware circuit, and the functions of part or all of the units or modules can be implemented by the design of the hardware circuit, and the hardware circuit can be understood as one or more processors; for example, in one implementation, the hardware circuit is an application-specific integrated circuit (ASIC), and the functions of part or all of the units or modules are implemented by the design of the logical relationship between the elements in the circuit; for another example, in another implementation, the hardware circuit is a programmable logic device (PLD), and taking a field programmable gate array (FPGA) as an example, it can include a large number of logic gate circuits, and the connection relationship between the logic gate circuits is configured by a configuration file, so as to implement the functions of part or all of the units or modules. All units or modules of the above device can be implemented in the form of processor invoking software, or all units or modules can be implemented in the form of hardware circuit, or part of the units or modules are implemented in the form of processor invoking software, and the remaining part is implemented in the form of hardware circuit.

[0429] In the embodiments of the present disclosure, the processor is a circuit with signal processing capability. In one implementation, the processor can be a circuit with instruction reading and running capability, such as a central processing unit (CPU), a microprocessor, a graphics processing unit (GPU) (which can be understood as a microprocessor), a digital signal processor (DSP), or the like. In another implementation, the processor can implement certain functions through a logical relationship of hardware circuit, and the logical relationship of the hardware circuit is fixed or reconfigurable. For example, the processor is a hardware circuit implemented by an application-specific integrated circuit (ASIC) or a programmable logic device (PLD), such as an FPGA. In the reconfigurable hardware circuit, the processor loads a configuration document to implement the configuration of the hardware circuit. It can be understood that the processor loads instructions to implement the functions of the above part or all units or modules. In addition, it can also be a hardware circuit designed for artificial intelligence, which can be understood as an ASIC, such as a neural network processing unit (NPU), a tensor processing unit (TPU), a deep learning processing unit (DPU), or the like.

[0430] FIG. 6a is a schematic diagram of the structure of the terminal 6100 according to an embodiment of the present disclosure. As shown in FIG. 6a, the terminal 6100 can include at least one of a transceiver module 6101, a processing module 6102, and the like. In some embodiments, the transceiver module is configured to transmit and / or receive information. Optionally, the transceiver module is configured to perform at least one of the communication steps of transmitting and / or receiving performed by the terminal in any of the methods described above. Details are not described herein again. Optionally, the processing module is configured to perform at least one of the other steps performed by the terminal in any of the methods described above. Details are not described herein again.

[0431] FIG. 6b is a structural diagram of the access network device 6200 according to an embodiment of the present disclosure. As shown in FIG. 6b, the access network device 6200 can include at least one of a transceiver module 6201, a processing module 6202, and the like. In some embodiments, the transceiver module is configured to transmit and / or receive information. Optionally, the transceiver module is configured to perform at least one of the communication steps (e.g., transmitting and / or receiving) performed by the access network device in any of the methods described above. Details are not described herein again. In some embodiments, the transceiver module can include a transmitting module and / or a receiving module. The transmitting module and the receiving module can be separate or integrated together. Optionally, the transceiver module can be replaced by a transceiver.

[0432] In some embodiments, the processing module can be a module or can include multiple sub-modules. Optionally, the multiple sub-modules perform all or part of the steps required to be performed by the processing module, respectively. Optionally, the processing module can be replaced by a processor.

[0433] FIG. 7a is a structural diagram of a communication device 9100 according to an embodiment of the present disclosure. The communication device 9100 can be a network device (e.g., an access network device, a core network device, or the like), a terminal (e.g., a user equipment or the like), a chip, a chip system, or a processor supporting the network device to implement any of the methods described above, or a chip, a chip system, or a processor supporting the terminal to implement any of the methods described above. The communication device 9100 can be configured to implement the methods described in the method embodiments described above. Details can be referred to the descriptions of the method embodiments described above.

[0434] As shown in FIG. 7a, the communication device 9100 includes one or more processors 9101. The processor 9101 can be a general processor or a special-purpose processor, for example, a baseband processor or a central processing unit. The baseband processor can be configured to process communication protocols and communication data, and the central processing unit can be configured to control the communication device (e.g., a base station, a baseband chip, a terminal device, a terminal device chip, a DU, a CU, or the like), execute programs, and process data of the programs. The communication device 9100 is configured to implement any of the methods described above.

[0435] In some embodiments, the communication device 9100 further includes one or more memories 9102 configured to store instructions. Optionally, all or part of the memory 9102 can also be located outside the communication device 9100.

[0436] In some embodiments, the communication device 9100 further includes one or more transceivers 9103. When the communication device 9100 includes one or more transceivers 9103, the transceiver 9103 performs at least one of the communication steps (e.g., transmitting and / or receiving) in the methods described above, and the processor 9101 performs at least one of the other steps.

[0437] In some embodiments, the transceiver can include a receiver and / or a transmitter, which can be separate or integrated together. Optionally, the terms transceiver, transceiving unit, transceiver, transceiving circuit, etc. can be replaced by each other, the terms transmitter, transmitting unit, transmitter, transmitting circuit, etc. can be replaced by each other, and the terms receiver, receiving unit, receiver, receiving circuit, etc. can be replaced by each other.

[0438] In some embodiments, the communication device 9100 can include one or more interface circuits 9104. Optionally, the interface circuit 9104 is connected with the memory 9102, and the interface circuit 9104 can be used to receive signals from the memory 9102 or other devices, and can be used to send signals to the memory 9102 or other devices. For example, the interface circuit 9104 can read instructions stored in the memory 9102 and send the instructions to the processor 9101.

[0439] The communication device 9100 described in the above embodiments can be a network device or a terminal, but the scope of the communication device 9100 described in the present disclosure is not limited thereto, and the structure of the communication device 9100 can not be limited by Figure 7a. The communication device can be a standalone device or can be part of a larger device. For example, the communication device can be: 1) a standalone integrated circuit (IC), or a chip, or a chip system or subsystem; (2) a set of one or more ICs, which can optionally also include storage components for storing data, programs; (3) an ASIC, such as a modem; (4) a module that can be embedded in other devices; (5) a receiver, a terminal device, a smart terminal device, a cellular phone, a wireless device, a handset, a mobile unit, a vehicle-mounted device, a network device, a cloud device, an artificial intelligence device, etc.; (6) other devices, etc.

[0440] Figure 7b is a structural schematic diagram of a chip 9200 according to an embodiment of the present disclosure. For the case where the communication device 9100 is a chip or a chip system, the structural schematic diagram of the chip 9200 shown in Figure 7b can be referred to, but is not limited thereto.

[0441] The chip 9200 includes one or more processors 9201, and the chip 9200 is configured to execute any of the above methods.

[0442] In some embodiments, the chip 9200 further includes one or more interface circuits 9202. Optionally, the interface circuit 9202 is connected with the memory 9203, and the interface circuit 9202 can be used to receive signals from the memory 9203 or other devices, and can be used to send signals to the memory 9203 or other devices. For example, the interface circuit 9202 can read instructions stored in the memory 9203 and send the instructions to the processor 9201.

[0443] In some embodiments, the interface circuit 9202 performs at least one of the communication steps of sending and / or receiving in the above-described methods, and the processor 9201 performs at least one of the other steps.

[0444] In some embodiments, the terms interface circuit, interface, transceiver pin, transceiver, etc. can be replaced by each other.

[0445] In some embodiments, the chip 9200 further includes one or more memories 9203 for storing instructions. Optionally, all or part of the memories 9203 can be outside the chip 9200.

[0446] The disclosure also proposes a storage medium having instructions stored thereon, which, when executed on the communication device 9100, causes the communication device 9100 to perform any of the above methods. Optionally, the storage medium is an electronic storage medium. Optionally, the storage medium is a computer readable storage medium, but is not limited to this, and it can also be a storage medium readable by other devices. Optionally, the storage medium can be a non-transitory storage medium, but is not limited to this, and it can also be a transitory storage medium.

[0447] The disclosure also proposes a program product which, when executed by the communication device 9100, causes the communication device 9100 to perform any of the above methods. Optionally, the program product is a computer program product.

[0448] The disclosure also proposes a computer program which, when executed on a computer, causes the computer to perform any of the above methods.

Claims

1. A communication method characterized by comprising: The method is performed by a terminal, and the method comprises: determining a key for a radio resource control (RRC) connection reestablishment procedure; wherein the key is used for encryption and / or integrity protection of a message (MSG4).

2. The method of claim 1, wherein, The method further comprises: determining a derivation manner of the key; wherein the derivation manner is one of: a horizontal derivation manner; a vertical derivation manner.

3. The method of claim 2, wherein, The determining of the derivation manner of the key comprises: determining the derivation manner of the key by at least one of: a handover type; a received first information.

4. The method of claim 3, wherein, The determining of the derivation manner of the key by the received first information comprises any of: in a case that the first information indicates the vertical derivation manner, determining the derivation manner of the key as the vertical derivation manner; in a case that the first information indicates the horizontal derivation manner, determining the derivation manner of the key as the horizontal derivation manner; in a case that the first information is not received, determining the derivation manner of the key as the vertical derivation manner; in a case that the first information is not received, determining the derivation manner of the key as the horizontal derivation manner.

5. The method according to claim 3 or 4, characterized in that, The determining of the derivation manner of the key by the handover type comprises: determining the derivation manner of the key based on a handover type indicated by a second information; the handover type is one of: a first handover type, the first handover type being an Xn handover; a second handover type, the second handover type being an NG handover; a third handover type, the third handover type being an intra-gNB handover; a fourth handover type, the fourth handover type being an intra-CU handover.

6. The method of claim 5, wherein, The determining of the derivation manner of the key based on the handover type indicated by the second information comprises one of: in a case that the second information indicates that a handover type of the handover is the first handover type, determining the derivation manner of the key as the vertical derivation manner; in a case that the second information indicates that the handover type of the handover is the second handover type, determining the derivation manner of the key as the horizontal derivation manner; in a case that the second information indicates that the handover type of the handover is the third handover type, determining the derivation manner of the key as the horizontal derivation manner; in a case that the second information indicates that the handover type of the handover is the fourth handover type, determining the derivation manner of the key as the horizontal derivation manner. The method further comprises:

7. The method of claim 1, wherein, receiving a third information; wherein the third information is used to indicate a next hop chaining count (NCC) used in the RRC connection reestablishment. The method further comprises:

8. The method of claim 7, wherein, determining that the handover fails and a next hop change parameter (NH) corresponding to the NCC is not used, and generating the NH based on the NCC. The method further comprises:

9. The method of claim 7, wherein, determining that the handover succeeds and the NCC indicated by the third information is the same as an NCC configured for the RRC connection reestablishment and the NH is not used, and generating the NH based on the NCC. The method further comprises:

10. The method according to any one of claims 1 to 9, characterized in that, receiving a fourth information in a case that an RRC connected state is entered; wherein the fourth information is used to indicate an inactive state radio network temporary identifier (I-RNTI), and the I-RNTI is used for the RRC connection reestablishment and / or an RRC connection resume. ​ 11. The method of claim 10, wherein, The I-RNTI is an identifier configured for each access network device, or an identifier configured for access network devices in a first set, the first set including at least two access network devices.

12. The method according to claim 10 or 11, characterized in that The I-RNTI is used to identify context information of the terminal and / or determine an access network device where the context information is located.

13. The method of claim 10 or 11, wherein, The receiving of the fourth information includes at least one of the following: The fourth information is received in response to determining access network device switching; The fourth information is received in response to determining intra-CU inter-CU switching.

14. A communication method, comprising: The method is performed by an access network device, and the method includes: sending first information to a terminal; The first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

15. The method of claim 14, wherein, The derivation manner is one of the following: horizontal derivation manner; vertical derivation manner.

16. The method of claim 14, wherein, The method further includes: sending third information to the terminal; The third information is used to indicate a next hop count NCC used in RRC connection reestablishment.

17. The method of claim 14, wherein, The method further includes: sending fourth information to the terminal in an RRC connected state; The fourth information is used to indicate an inactive state radio network temporary identifier I-RNTI, and the I-RNTI is used for RRC connection reestablishment and / or RRC connection recovery.

18. The method of claim 17, wherein, The I-RNTI is an identifier configured for each access network device, or an identifier configured for access network devices in a first set, the first set including at least two access network devices.

19. The method according to claim 17 or 18, characterized in that The I-RNTI is used to identify context information of the terminal and / or determine an access network device where the context information is located.

20. The method of any one of claims 17-19, wherein, The sending of the fourth information to the terminal includes at least one of the following: The fourth information is sent to the terminal in response to determining access network device switching; The fourth information is sent to the terminal in response to determining intra-CU inter-CU switching.

21. The method of claim 14, wherein, The derivation manner adopted by the terminal is a vertical derivation manner, and the method further includes: determining that the access network device has an unused next hop variable NH, and generating the key based on the NH and the vertical derivation manner.

22. The method of claim 21, wherein, The method further includes: determining that the access network device does not have the unused NH, and sending fifth information to a core network device; The fifth information is used to request the core network device to configure the NH.

23. The method of claim 14, wherein, The derivation manner adopted by the terminal is a horizontal derivation manner, and the method further includes one of the following: determining that the access network device has the unused NH, and that a source serving access device and a target access network device corresponding to RRC connection reestablishment are the same access network device, performing intra-gNB switching and performing key isolation using the NH after reestablishing the RRC connection; determining that the access network device has the unused NH, and discarding the NH.

24. A method of communication, comprising: The method includes: a network device sends first information to a terminal; The first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message MSG4 in an RRC connection reestablishment procedure.

25. A terminal, characterized by The terminal comprises: a transceiver module configured to: determine a key for a radio resource control (RRC) connection reestablishment procedure; wherein the key is used for encryption and / or integrity protection of a message (MSG4) of the RRC connection reestablishment procedure.

26. An access network device, comprising: The access network device comprises: a transceiver module configured to: send first information to the terminal; wherein the first information is used to indicate a derivation manner of a key; and the key is used for encryption and / or integrity protection of a message (MSG4) of the RRC connection reestablishment procedure.

27. A communication system comprising a terminal and an access network device, the terminal being configured to implement the method of any one of claims 1-15, and the access network device being configured to implement the method of any one of claims 16-22.

28. A terminal, characterized by The terminal comprises: one or more processors; wherein the terminal is configured to implement the method of any one of claims 1-13.

29. An access network device, comprising: The access network device comprises: one or more processors; wherein the access network device is configured to implement the method of any one of claims 14-23.

30. A computer program product comprising computer programs or instructions, characterized in that, The computer program or instructions, when executed by a processor, implement the steps of the method of any one of claims 1-13, 14-23.

31. A storage medium, characterized by The storage medium stores instructions, which, when executed on a communication device, cause the communication device to perform the method of any one of claims 1-13, 14-23.

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