Method for supporting access to a closed network, UE, base station, and readable storage medium

Abstract

A method for supporting a private network (NPN) by a first central unit (CU) of a first base station in a wireless communication system comprises the steps of: receiving an F1 setup request from a first distribution unit (DU) of the first base station, the request including at least one of a first closed access network (CAG) identifier list or a first network identifier (NID) list; transmitting an NG setup request to an access and mobility management function unit (AMF), the request including at least one of a first CAG identifier list or a first NID list; receiving an NG setup response from the AMF; and transmitting an F1 setup response to the first DU.

Description

Technology Field

[0001] The present disclosure relates to the field of wireless communication technology, and in particular, to a method for supporting access to a closed network, a UE, a base station, and a computer-readable storage medium. Background Technology

[0002] Fifth-generation (5G) mobile communication technology is not a single wireless technology, but a convergence of existing wireless communication technologies. Currently, LTE's peak rate can reach 100 Mbps, while 5G's peak rate will reach 10 Gbps, which is 100 times faster than 4G. Existing 4G networks have limitations in processing capacity and cannot support certain types of traffic, such as high-definition video, high-quality voice, augmented reality, and virtual reality. 5G will meet the demands of increasing mobile traffic and solve the problems faced by 4G networks by introducing more advanced technologies, along with higher spectrum efficiency, more spectrum resources, and denser cells, to build a network community with high transmit rates, high capacity, low latency, high reliability, and a superior user experience. As illustrated in Fig. 1, the 5G architecture includes a 5G access network and a 5G core network. UEs communicate with the data network through the access network and the core network.

[0003] The 5G access network includes 5G base stations (gNB) and LTE base stations (eNB) connected to the 5G core network, collectively referred to as NG-RAN. The protocol stack on the base stations is illustrated in FIG. 2, and the user plane of the base station includes the Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP), Radio Link Control Protocol (RLC), Media Access Control Protocol (MAC), and the physical layer, while the control plane of the base station includes the Radio Connection Control Protocol (RRC), PDCP, RLC, MAC, and the physical layer. The control plane also needs to support the interface protocol (Xn) between base stations and the protocol (NG) between the base station and the core network.

[0004] 5G supports services with higher traffic rates and stricter latency requirements, such as ultra-reliable and low-latency communications. To support reliable low-latency services, shorter transmit time intervals are introduced to support low latency, and data replication transmission mechanisms are introduced to support reliability. In the 5G architecture, due to advancements in wireless technology, functional modules that were originally located on the same base station are separated; some functional modules are moved closer to the user, while others are pooled, virtualized, and centrally deployed. In other words, the base station can be divided into two parts, one being a central control unit (CU) and the other a distribution unit (DU). The DU is closer to the user, while the CU is located further away from the antenna; they support multi-antenna connectivity and can improve network performance; a single CU can connect multiple DUs, and functions on the CU can be virtualized. The CU and DU are connected via an F1 interface, also known as a fronthall interface or fronthall connection. The functions of RRC and PDCP are implemented on the CU, and the functions of RLC, MAC, and the physical layer are implemented on the DU.

[0005] In a 5G architecture divided into CUs and DUs, it is necessary to consider how to support Closed Access Groups (CAGs) or standalone non-public network technologies at the base stations where cells are located. Specifically, the following needs to be considered:

[0006] (1) A method to ensure that when a UE accesses a network, particularly through an architecture where CUs and DUs are separated, users belonging to a CAG or private network can access cells of the closed access group or private network, and that users not belonging to a CAG can access cells that support the CAG, and that users not belonging to a private network can access the private network.

[0007] (2) A method to ensure that when a UE performs a handover including a handover of NG and Xn, particularly when the handover is performed under an architecture where CU and DU are separated, users belonging to a CAG or private network are transferred to cells of the closed access group or private network, and users not belonging to a CAG are not transferred to cells that support the CAG, and users not belonging to a private network are not transferred to a private network.

[0008] (3) A method to ensure that when a UE performs RRC re-establishment in a new cell or when a UE in inactive mode restores an RRC connection in a new cell, the UE re-establishes only in cells of the corresponding closed access group or private network, prevents users not belonging to the CAG from re-establishing in cells that support the CAG, and prevents users not belonging to the private network from re-establishing in the private network. means of solving the problem

[0009] Taking into account the disadvantages of existing embodiments, the present disclosure proposes a method, a UE, a base station, and a computer-readable storage medium that support access to a closed network to solve the problem of a method that enables users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access said CAG cell or SNPN cell. Brief explanation of the drawing

[0010] In order to explain the technical solutions of the embodiments of the present disclosure more clearly, the drawings used in the description of the embodiments of the present disclosure will be briefly described below. FIG. 1 is a diagram of a 5G system architecture; FIG. 2 is a diagram of a base station protocol architecture; FIG. 3a is a schematic flowchart of a method for supporting access to a closed network according to one embodiment of the present disclosure; FIG. 3b is a schematic flowchart of another method supporting access to a closed network according to one embodiment of the present disclosure; FIG. 4 is a schematic flowchart of another method supporting access to a closed network according to one embodiment of the present disclosure; FIG. 5 is a schematic flowchart of another method for supporting access to a closed network according to one embodiment of the present disclosure; FIG. 6 is a schematic flowchart of another method for supporting access to a closed network according to one embodiment of the present disclosure; FIG. 7 is a schematic flowchart of another method for supporting access to a closed network according to one embodiment of the present disclosure; FIG. 8 is a schematic flowchart of another method for supporting access to a closed network according to one embodiment of the present disclosure; FIG. 9 is a schematic diagram of an interface establishment process provided by one embodiment of the present disclosure; FIG. 10 is a schematic diagram of a process in which a UE accesses a CAG cell according to one embodiment of the present disclosure; FIG. 11 is a schematic diagram of a process in which a UE performs an Xn handover according to one embodiment of the present disclosure; FIG. 12 is a schematic diagram of a process in which a UE performs an NG handover according to one embodiment of the present disclosure; FIG. 13 is a schematic diagram of a process in which a UE re-selects a new cell to initiate RRC re-establishment after a wireless link failure occurs in a previous cell according to one embodiment of the present disclosure; FIG. 14 is a schematic diagram of a process for establishing a dual connection according to one embodiment of the present disclosure; FIG. 15a is a schematic structural diagram of a first base station according to one embodiment of the present disclosure; FIG. 15b is a schematic structural diagram of a second base station according to one embodiment of the present disclosure; FIG. 16 is a schematic structural diagram of a UE according to one embodiment of the present disclosure; FIG. 17 is a schematic structural diagram of a first CU according to one embodiment of the present disclosure; FIG. 18 is a schematic structural diagram of a CU according to one embodiment of the present disclosure; FIG. 19 is a schematic structural diagram of a destination base station according to one embodiment of the present disclosure; FIG. 20 is a schematic structural diagram of a primary base station according to one embodiment of the present disclosure; FIG. 21 is a schematic structural diagram of a base station, a base station CU, or a base station DU according to one embodiment of the present disclosure. Specific details for implementing the invention

[0011] According to a first aspect of the present disclosure, a method used at a first base station to support access to a closed network comprises:

[0012] A step of receiving a radio resource control (RRC) re-establishment request transmitted by user equipment (UE);

[0013] A step of transmitting a UE context extraction request to a second base station based on an RRC re-establishment request;

[0014] A step of receiving a UE context extraction response message transmitted by a second base station, wherein the UE context extraction response message is determined by the second base station based on a first determination rule; and

[0015] A step of transmitting an RRC re-establishment response message to a UE to support the UE in accessing a closed network based on a UE context extraction response message, wherein the closed network includes at least one of a closed access group (CAG) and a free-standing private network (SNPN).

[0016] According to a second aspect of the present disclosure, a method used at a second base station to support access to a closed network comprises:

[0017] A step of receiving a UE context extraction request transmitted by a first base station;

[0018] A step of transmitting a UE context extraction response message to a first base station, wherein the UE context extraction response message is determined based on a first determination rule to support the UE in accessing a closed network, and the closed network includes at least one of a closed access group (CAG) and a free-standing private network (SNPN).

[0019] According to a third aspect of the present disclosure, a method used in a UE to support access to a closed network comprises:

[0020] A step of transmitting an RRC re-establishment request to the first base station;

[0021] A step of receiving an RRC re-establishment response message transmitted by a first base station; and

[0022] A step of accessing a closed network, wherein the closed network comprises at least one of a closed access group (CAG) and a free-standing private network (SNPN).

[0023] According to a fourth aspect of the present disclosure, a method used in a first central control unit (CU) to support access to a closed network comprises:

[0024] A step of receiving an F1 establishment request transmitted by a distribution unit (DU), wherein the F1 establishment request comprises at least one of a list of closed access group (CAG) identifiers and a freestanding private network (SNPN) identifier;

[0025] A step of transmitting an NG establishment request to an access and mobility management function (AMF) of a core network, wherein the NG establishment request comprises at least one of a list of CAG identifiers and / or an SNPN identifier;

[0026] A step of receiving an NG establishment response transmitted by the AMF;

[0027] Step of transmitting an F1 establishment response to the DU;

[0028] A step of transmitting an Xn establishment request to a second CU, wherein the Xn establishment request comprises at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network comprises at least one of a CAG and an SNPN; and

[0029] A step of receiving an established response transmitted by Xn a second CU, wherein the Xn established response comprises at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network comprises at least one of a CAG and an SNPN.

[0030] According to a fifth aspect of the present disclosure, a method used in a control unit (CU) to support access to a closed network comprises:

[0031] A step of receiving an initial uplink (UL) RRC message transfer transmitted by the DU;

[0032] A step of transmitting a downlink (DL) RRC message to the DU;

[0033] A step of receiving a UL RRC message transmitted by the DU;

[0034] A step of transmitting an initial UE message to an AMF, wherein the initial UE message comprises at least one of a cell global unique identifier of the cell to which the UE is located, a list of CAG identifiers supported by the cell, a PLMN (public land mobile network) identifier, and a NID (network identifier);

[0035] A step of receiving an initial context establishment request message transmitted by AMF;

[0036] A step of transmitting a UE context establishment request message to a DU, wherein the UE context establishment request message comprises at least one of a list of CAG identifiers allowed for the UE to access and instruction information indicating whether the UE is allowed to access only CAG cells;

[0037] Receiving a UE context establishment response transmitted by the DU; and

[0038] A step of transmitting an initial context establishment response message to an AMF to support the UE in accessing a closed network, wherein the closed network includes at least one of a CAG and an SNPN.

[0039] According to a sixth aspect of the present disclosure, a method used at a destination base station to support access to a closed network comprises:

[0040] A step of receiving a handover request message transmitted by a source base station, wherein the handover request message comprises at least one of information of a destination base station, information of a destination cell, a list of CAG identifiers allowed for access by a UE, and instruction information for indicating whether the UE is allowed to access only the CAG cell;

[0041] A step of transmitting a handover response message to the source base station;

[0042] A step of receiving a handover completion message for a UE switching from a source base station to a destination base station;

[0043] A step of transmitting a route switching request message to an AMF, wherein the route switching request message comprises at least one of a list of CAG identifiers for a cell, a PLMN identifier for a cell, and an NID; and

[0044] A step of receiving a route switching response message transmitted by an AMF, wherein the route switching response message comprises at least one of a list of CAG identifiers that the UE is allowed to access to support the UE in accessing a closed network and instruction information for indicating whether the UE is allowed to access only a CAG cell, and wherein the closed network comprises at least one of a CAG and an SNPN.

[0045] According to a seventh aspect of the present disclosure, a method used in a primary base station to support access to a closed network comprises:

[0046] A step of transmitting a secondary base station establishment request message to a secondary base station, wherein the secondary base station establishment request message comprises at least one of a list of CAG identifiers that a UE is allowed to access and instruction information for indicating whether the UE is allowed to access only a CAG cell; and

[0047] A step of receiving a secondary base station establishment response message transmitted by a secondary base station to support a UE in accessing a closed network, wherein the closed network includes at least one of a CAG and an SNPN.

[0048] According to the eighth aspect of the present disclosure, a first base station is provided and comprises: a first processing module configured to receive a radio resource control (RRC) re-establishment request transmitted by a user equipment (UE);

[0049] A second processing module configured to transmit a UE context extraction request to a second base station based on an RRC re-establishment request;

[0050] A third processing module configured to receive a UE context extraction response message transmitted by a second base station, wherein the UE context extraction response message is determined by the second base station based on a first decision rule; and

[0051] A fourth processing module configured to send an RRC re-establishment response message to a UE to support the UE in accessing a closed network based on a UE context extraction response message, wherein the closed network comprises at least one of a closed access group (CAG) and a free-standing private network (SNPN).

[0052] According to a ninth aspect of the present disclosure, a second base station is provided and comprises: a receive request module configured to receive a UE context extraction request transmitted by a first base station; and

[0053] A message transmission module configured to transmit a UE context extraction response message to a first base station, wherein the UE context extraction response message is determined based on a first decision rule to support a UE in accessing a closed network, and the closed network includes at least one of a closed access group (CAG) and a freestanding private network (SNPN).

[0054] According to the tenth aspect of the present disclosure, a UE is provided and comprises the following:

[0055] A fifth processing module configured to transmit an RRC re-establishment request to a first base station;

[0056] A sixth processing module configured to receive an RRC re-establishment response message transmitted by a first base station; and

[0057] An access processing module configured to access a closed network, wherein the closed network comprises at least one of a closed access group (CAG) and a free-standing private network (SNPN).

[0058] According to the eleventh aspect of the present disclosure, a first CU is provided and comprises the following:

[0059] A seventh processing module configured to receive an F1 establishment request transmitted by a distribution unit (DU), wherein the F1 establishment request comprises at least one of a list of closed access group (CAG) identifiers and a freestanding private network (SNPN) identifier;

[0060] An eighth processing module configured to transmit an NG establishment request to the Access and Mobility Management Function (AMF) of a core network, wherein the NG establishment request comprises at least one of a list of CAG identifiers and / or an SNPN identifier;

[0061] A ninth processing module configured to receive an NG establishment response transmitted by the AMF;

[0062] A 10th processing module configured to transmit an F1 establishment response to the DU;

[0063] A first processing module configured to transmit an Xn establishment request to a second CU, wherein the Xn establishment request comprises at least one of a list of CAG identifiers and / or SNPN identifiers to support a UE in accessing a closed network, and the closed network comprises at least one of a CAG and an SNPN; and

[0064] A 12th processing module configured to receive an Xn establishment response transmitted by a 2nd CU, wherein the Xn establishment response comprises at least one of a list of CAG identifiers and / or SNPN identifiers to support a UE in accessing a closed network, and the closed network comprises at least one of a CAG and an SNPN.

[0065] According to the 12th aspect of the present disclosure, a CU is provided and comprises the following:

[0066] A receiving processing module configured to receive an initial UL RRC message transmitted by the DU;

[0067] A 13th processing module configured to transmit a DL RRC message to the DU;

[0068] A 14th processing module configured to receive UL RRC message transmissions sent by the DU;

[0069] A 15th processing module configured to transmit an initial UE message to an AMF, wherein the initial UE message comprises at least one of a global unique identifier of the cell to which the UE is located, a list of CAG identifiers supported by the cell, a PLMN identifier, and an NID;

[0070] A 16th processing module configured to receive an initial context establishment request message transmitted by the AMF;

[0071] A 17th processing module configured to transmit a UE context establishment request message to a DU, wherein the UE context establishment request message comprises at least one of a list of CAG identifiers allowed for the UE to access and instruction information for indicating whether the UE is allowed to access only CAG cells;

[0072] A 18th processing module configured to receive a UE context establishment response transmitted by the DU; and

[0073] A 19th processing module configured to send an initial context establishment response message to an AMF to support a UE in accessing a closed network, wherein the closed network comprises at least one of a CAG and an SNPN.

[0074] According to the 13th aspect of the present disclosure, a destination base station is provided and comprises the following:

[0075] A 20th processing module configured to receive a handover request message transmitted by a source base station, wherein the handover request message comprises at least one of information of a destination base station, information of a destination cell, a list of CAG identifiers allowed for access by a UE, and instruction information for indicating whether the UE is allowed to access only the CAG cell;

[0076] A 21st processing module configured to transmit a handover response message to a source base station;

[0077] A 22nd processing module configured to receive a handover completion message for a UE switching from a source base station to a destination base station;

[0078] A 23rd processing module configured to transmit a route switching request message to an AMF, wherein the route switching request message comprises at least one of a list of CAG identifiers for a cell, a PLMN identifier for a cell, and an NID; and

[0079] A 24th processing module configured to receive a route switching response message transmitted by an AMF, wherein the route switching response message includes at least one of a list of CAG identifiers that the UE is allowed to access and instruction information for indicating whether the UE is allowed to access only CAG cells to support the UE in accessing a closed network, and wherein the closed network includes at least one of a CAG and an SNPN.

[0080] According to the 14th aspect of the present disclosure, a primary base station is provided and comprises the following:

[0081] A 25th processing module configured to transmit a secondary base station establishment request message to a secondary base station, wherein the secondary base station establishment request message comprises at least one of a list of CAG identifiers allowed for access by a UE and instruction information for indicating whether the UE is allowed to access only a CAG cell; and

[0082] A 26th processing module configured to receive a secondary base station establishment response message transmitted by a secondary base station to support a UE in accessing a closed network, wherein the closed network comprises at least one of a CAG and an SNPN.

[0083] According to the 15th aspect, the present disclosure provides a computer-readable storage medium that stores a computer program that implements a method for supporting access to a closed network according to the first to sixth aspects of the present disclosure when executed by a processor.

[0084] The technical solutions provided in the embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0085] Additional aspects and advantages of the present disclosure will be given in the following description, which will become apparent from the following description or will be known through the practice of the present disclosure.

[0086] Embodiments of the present disclosure are described in detail below, and examples of the embodiments are illustrated in the drawings. Throughout the drawings, identical or similar reference numerals are used to describe identical or similar elements or elements having identical or similar functions. The embodiments described below with reference to the accompanying drawings are illustrative and are not to be interpreted as limiting the present disclosure, but are used only to explain the present disclosure.

[0087] Those skilled in the art should understand that the singular forms corresponding to the use of “a,” “an,” “above,” and “the” include plural references unless the context explicitly indicates otherwise. It should be further understood that the expressions “comprising” or “comprising” as used in the specification of this disclosure mean the presence of features, integers, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, actions, elements, components, and / or combinations thereof. When an element is referred to as being “connected” or “coupled” to another element, it should be understood that it may be directly connected or coupled to the other element, or that an intervening element may exist. Furthermore, the terms “connected” or “coupled” as used in this disclosure may include wireless connection or wireless coupling. The phrase “and / or” as used in this disclosure includes all or any one of the associated listed items and all combinations thereof.

[0088] Embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings to further clarify the purposes, technical solutions, and advantages of the present disclosure.

[0089] Example 1

[0090] One embodiment of the present disclosure provides a method used at a first base station to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 3a. The method comprises the following steps:

[0091] Step S101: Receiving a request for re-establishment of wireless resource control (RRC) transmitted by user equipment (UE).

[0092] Step S102: Transmitting a UE context extraction request to the second base station based on an RRC re-establishment request;

[0093] Step S103: A step of receiving a UE context extraction response message transmitted by the second base station, wherein the UE context extraction response message is determined by the second base station based on the first determination rule.

[0094] Step S104: A step of sending an RRC re-establishment response message to the UE to support the UE in accessing a closed network based on a UE context extraction response message, wherein the closed network includes at least one of a Closed Access Group (CAG) and a Self-Reliant Private Network (SNPN).

[0095] In an embodiment of the present disclosure, a first base station receives a radio resource control (RRC) re-establishment request transmitted by a user equipment (UE); the first base station transmits a UE context extraction request to a second base station based on the RRC re-establishment request; the first base station receives a UE context extraction response message transmitted by the second base station, the UE context extraction response message being determined by the second base station based on a first determination rule; and the first base station transmits an RRC re-establishment response message to the UE to support the UE in accessing a closed network based on the UE context extraction response message, wherein the closed network includes at least one of a closed access group (CAG) and a self-contained private network (SNPN). In this way, users of the closed access group (CAG) or users belonging to the self-contained private network (SNPN) are enabled to access the corresponding CAG cell or SNPN cell.

[0096] Alternatively, the first decision rule includes at least one of the following:

[0097] The second base station determines whether the CAG supported by the cell of the first base station is in the list of CAG identifiers allowed by the UE, and if so, the second base station transmits a UE context extraction response message to the first base station, and if not, the second base station transmits a UE context extraction failure message to the first base station;

[0098] The second base station determines whether the SNPN identifier for the cell of the first base station is the same as the SNPN identifier for the cell of the second base station, and if so, the second base station sends a UE context extraction response message to the first base station, and if not, the second base station sends a UE context extraction failure message to the first base station.

[0099] Alternatively, a request for UE context extraction is transmitted to a second base station, and the message carries identifiers of a CAG or an SNPN supported by a cell of the first base station; a UE context extraction failure message transmitted by the second base station is received, and the UE is prohibited from accessing a closed network including at least one of a CAG and an SNPN, and the message carries the reason for the failure.

[0100] One embodiment of the present disclosure provides a method used at a second base station to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 3b. The method comprises the following steps:

[0101] Step S1001: Receiving a UE context extraction request transmitted by the first base station.

[0102] Step S1002: A step of transmitting a UE context extraction response message to a first base station, wherein the UE context extraction response message is determined based on a first decision rule to support the UE in accessing a closed network, and the closed network includes at least one of a Closed Access Group (CAG) and a Self-contained Private Network (SNPN).

[0103] Alternatively, the first decision rule includes at least one of the following:

[0104] The second base station determines whether the CAG supported by the cell of the first base station is in the list of CAG identifiers allowed by the UE, and if so, the second base station transmits a UE context extraction response message to the first base station, and if not, the second base station transmits a UE context extraction failure message to the first base station;

[0105] The second base station determines whether the SNPN identifier for the cell of the first base station is the same as the SNPN identifier for the cell of the second base station, and if so, the second base station sends a UE context extraction response message to the first base station, and if not, the second base station sends a UE context extraction failure message to the first base station.

[0106] One embodiment of the present disclosure provides another method used in a UE to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 4. The method comprises the following steps:

[0107] Step S201: A step of transmitting an RRC re-establishment request to the first base station.

[0108] Step S202: Receiving an RRC re-establishment response message transmitted by the first base station.

[0109] Step S203: A step of accessing a closed network, wherein the closed network includes at least one of a Closed Access Group (CAG) and a Freestanding Private Network (SNPN).

[0110] One embodiment of the present disclosure provides another method used in a first central control unit (CU) to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 5. The method comprises the following steps:

[0111] Step S301: A step of receiving an F1 establishment request transmitted by a distribution unit (DU), wherein the F1 establishment request includes at least one of a list of closed access group (CAG) identifiers and / or a freestanding private network (SNPN) identifier.

[0112] Step S302: A step of transmitting an NG establishment request to the Access and Mobility Management Function (AMF) of the core network, wherein the NG establishment request includes at least one of a list of CAG identifiers and / or SNPN identifiers.

[0113] Step S303: Step of receiving the NG establishment response transmitted by the AMF.

[0114] Step S304: Step of transmitting the F1 established response to the DU.

[0115] Step S305: A step of transmitting an Xn establishment request to the second CU, wherein the Xn establishment request includes at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN.

[0116] Step S306: A step of receiving an established response transmitted by Xn a second CU, wherein the Xn established response includes at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN.

[0117] Alternatively, when the F1 establishment request includes a list of CAG identifiers, the information carried by the NG establishment request includes at least one of the following:

[0118] Information regarding a base station identifier, a base station routing area, a base station operator identifier, a list of CAG identifiers supported by the base station, and cells supported by the base station, wherein the information regarding cells supported by the base station includes a cell identity, a cell operator identifier, a cell routing area identifier, and a list of CAG identifiers supported by the cell.

[0119] Alternatively, when the F1 establishment request includes an SNPN identifier, the information carried by the NG establishment request includes at least one of the following:

[0120] Public Land Mobility Network (PLMN) identifier, and Network Identifier (NID).

[0121] One embodiment of the present disclosure provides another method used in a CU to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 6. The method comprises the following steps:

[0122] Step S401: Receiving the delivery of an initial UL RRC message transmitted by the DU.

[0123] Step S402: A step of transmitting a DLRRC message to the DU.

[0124] Step S403: Receiving the delivery of a UL RRC message transmitted by the DU.

[0125] Step S404: A step of transmitting an initial UE message to an AMF, wherein the initial UE message includes at least one of the cell global unique identifier of the cell to which the UE is located, a list of CAG identifiers supported by the cell, a PLMN identifier, and an NID.

[0126] Step S405: Receiving an initial context establishment request message sent by the AMF.

[0127] Step S406: A step of sending a request message to establish a UE context to the DU, wherein the request message to establish a UE context includes at least one of a list of CAG identifiers that the UE is allowed to access and instruction information indicating whether the UE is allowed to access only the CAG cell.

[0128] Step S407: Receiving a UE context establishment response transmitted by the DU.

[0129] Step S408: A step of sending an initial context establishment response message to the AMF to support the UE in accessing a closed network, wherein the closed network includes at least one of a CAG and an SNPN.

[0130] Alternatively, the initial UL RRC message delivery message includes at least one of the following:

[0131] Identifier for F1 assigned by DU to the UE;

[0132] Cell global identifier (CGI) of a cell accessed by the UE;

[0133] If the cell accessed by the UE supports CAG, the initial UL RRC message delivery additionally carries a list of CAG identifiers supported by the cell;

[0134] If the cell accessed by the UE belongs to an SNPN, the initial UL RRC message delivery additionally carries a PLMN identifier and an NID;

[0135] It is a cell-radio network temporary identifier (C-RNTI) assigned to the UE by the DU, and the C-RNTI is a unique identifier used to identify the UE's RRC connection and scheduling;

[0136] It is an RRC container from DU to CU, and the RRC container contains cell group configuration information that includes information required to establish SRB1.

[0137] Alternatively, the initial context establishment request message includes at least one of the following:

[0138] Identifier of the NG interface assigned to the UE by the AMF, the UE's radio capability, the UE's encryption capability, information related to the establishment of a data session, a list of CAG identifiers allowed to be accessed by the UE, and indication information indicating whether the UE is allowed to access only the CAG cell.

[0139] One embodiment of the present disclosure provides another method used at a destination base station to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 7. The method comprises the following steps:

[0140] Step S501: A step of receiving a handover request message transmitted by a source base station, wherein the handover request message includes at least one of information of a destination base station, information of a destination cell, a list of CAG identifiers allowed for access by the UE, and instruction information for indicating whether the UE is allowed to access only the CAG cell.

[0141] Step S502: A step of transmitting a handover response message to the source base station.

[0142] Step S503: Receiving a handover completion message for a UE switching from a source base station to a destination base station.

[0143] Step S504: A step of transmitting a route switching request message to the AMF, wherein the route switching request message includes at least one of a list of CAG identifiers for the cell, a PLMN identifier for the cell, and an NID.

[0144] Step S505: A step of receiving a route switching response message transmitted by the AMF, wherein the route switching response message includes at least one of a list of CAG identifiers that the UE is allowed to access in order to support the UE in accessing a closed network and instruction information for indicating whether the UE is allowed to access only a CAG cell, and the closed network includes at least one of a CAG and an SNPN.

[0145] One embodiment of the present disclosure provides another method used at a primary base station to support access to a closed network, and a schematic flowchart of the method is shown in FIG. 8. The method comprises the following steps:

[0146] Step S601: A step of transmitting a secondary base station establishment request message to a secondary base station, wherein the secondary base station establishment request message includes at least one of a list of CAG identifiers that the UE is allowed to access and instruction information for indicating whether the UE is allowed to access only the CAG cell.

[0147] Step S602: A step of receiving a secondary base station establishment response message transmitted by a secondary base station to support the UE in accessing a closed network, wherein the closed network includes at least one of a CAG and an SNPN.

[0148] The technical solutions provided in the embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0149] Example 2

[0150] A method for supporting access to a closed network according to Example 1 above of the present disclosure is described in detail in the following examples.

[0151] FIG. 9 is a schematic diagram of an interface establishment process provided by one embodiment of the present disclosure. A base station is divided into a base station centralized control unit (CU) and a base station distribution unit (DU), where one DU may be connected to multiple CUs, and one CU may be connected to multiple DUs. The base station may be a 5G base station, an LTE base station, or a base station of another access mode. In this embodiment, a 5G base station is used as an example. If other systems are used, the corresponding interfaces and message names are changed accordingly. As illustrated in FIG. 9:

[0152] Step 901: The DU sends an F1 establishment request message to the CU.

[0153] The F1 establishment request message contains a group of information about cells. The information about these cells is set for the DU by the OAM, and these cells are ready to be activated. The cell information includes unique identifiers of the cell, such as the physical cell identifier (PCI) and the cell global identifier (CGI), and the cell operator identifier (e.g., PLMN ID).

[0154] If the cell supports a Closed Access Group (CAG), the cell information further includes a CAG identifier, which indicates which CAG is supported by the cell. The CAG identifier is unique under the PLMN, and a single cell can support multiple CAGs; in other words, the cell information may include a list of CAG identifiers. A single CAG identifier may also have a corresponding readable network name used to display to the user. The user can manually select a CAG based on the readable network name.

[0155] The CU obtains the cell's CAG identifier. When a UE accesses a cell, it is determined whether to allow the UE to access it based on the CAG identifiers supported by the accessed cell and the list of CAGs the UE is allowed to access. Alternatively, when a UE performs a handover, it is determined whether to allow the UE to handover it based on the CAG identifiers supported by the destination cell and the list of CAGs the UE is allowed to access.

[0156] If the cell belongs to a self-supporting private network (SNPN), the cell information in the F1 establishment request message includes a PLMN identifier and a network identifier (NID). The PLMN identifier and the NID are combined to identify the SNPN. The NID may be a locally maintained identifier, which is not a unique identifier across the entire network, or it may be a unique identifier across the entire network. A single PLMN ID may have multiple NIDs.

[0157] Step 902: CU sends the AMF to the NG establishment request message.

[0158] If the NG interface is not established between the CU and the AMF, the CU sends an NG establishment request message to the AMF. If the NG interface is established between the CU and the AMF, the CU sends a base station configuration update request to the AMF.

[0159] If the cell information received in step 901 includes a CAG identifier supported by the cell, the NG establishment request message carries the base station identifier, the base station routing area and the base station operator identifier, and the message additionally carries a list of CAG identifiers supported by the base station, or the NG establishment request message additionally carries information about cells supported by the base station. The information about the cells includes the cell identity, the cell operator identifier, the cell routing area identifier, and a list of CAG identifiers supported by the cell.

[0160] If the cell belongs to a self-supporting private network (SNPN), the NG establishment request message includes PLMN identifiers supported by the base station and additionally includes a network identifier (NID). The PLMN identifiers and the NID are combined to identify the SNPN, which is referred to as the SNPN identifier. The NID may be a locally maintained identifier, which is not a unique identifier across the entire network, or it may be a unique identifier across the entire network. A single PLMN ID may have multiple NIDs. Alternatively, the NG establishment request message additionally carries information about cells supported by the base station. The cell information includes the cell identity, the cell operator identifier, and the network identifier (NID).

[0161] Alternatively, the AMF obtains the base station's CAG identifier. When the UE performs a handover, for example, an NG handover, the AMF knows the handover destination base station or destination cell from the handover request message transmitted by the source base station. The AMF determines whether to allow the UE to switch to the destination base station based on the CAG identifiers supported by the destination base station obtained from the NG interface establishment request message and the stored CAG list to which the UE is allowed to access. If none of the CAG identifiers supported by the destination base station are in the CAG list to which the UE is allowed to access, the AMF determines that the UE is not allowed to access the destination base station. The AMF may directly transmit a handover refusal to the source base station. The handover refusal message may indicate the reason why the handover was denied; for example, the reason for the refusal is that the destination base station / destination cell is not allowed to be accessed.

[0162] Alternatively, the AMF obtains the cell's CAG identifier. When a UE performs a handover, for example, an NG handover, the AMF knows the handover destination cell from the handover request message transmitted by the source base station. The AMF determines whether to allow the UE to switch to the destination cell based on the CAG identifiers supported by the destination cell obtained from the NG interface establishment request message and the stored CAG list to which the UE is allowed to access. If none of the CAG identifiers supported by the destination cell are in the CAG list to which the UE is allowed to access, the AMF determines that the UE is not allowed to access the destination cell. The AMF may directly transmit a handover refusal to the source base station. The handover refusal message may indicate the reason why the handover was denied; for example, the reason for the refusal is that the destination base station / destination cell is not allowed to be accessed.

[0163] Alternatively, the AMF obtains the base station's SNPN identifier. When the UE performs a handover, for example, an NG handover, the AMF knows the handover destination base station or destination cell from the handover request message transmitted by the source base station. Based on the SNPN identifiers supported by the destination base station obtained from the NG interface establishment request message and the UE's stored authentication information, the AMF determines whether to allow the UE to switch to the destination base station. If none of the SNPN identifiers supported by the destination base station are on the list of SNPNs allowed for UE access, the AMF determines that the UE is not allowed to access the destination base station. The AMF may directly transmit a handover refusal to the source base station. The handover refusal message may indicate the reason why the handover was denied; for example, the reason for the refusal is that the destination base station / destination cell is not allowed to be accessed.

[0164] Alternatively, the AMF obtains the cell's SNPN identifier. When the UE performs a handover, for example, an NG handover, the AMF knows the handover destination cell from the handover request message transmitted by the source base station. Based on the SNPN identifiers supported by the destination cell obtained from the NG interface establishment request message and the UE's stored authentication information, the AMF determines whether to allow the UE to switch to the destination cell. If none of the SNPN identifiers supported by the destination cell are in the list of SNPNs allowed for UE access, the AMF determines that the UE is not allowed to access the destination cell. The AMF may directly transmit a handover refusal to the source base station. The handover refusal message may indicate the reason why the handover was denied; for example, the reason for the refusal is that the destination base station / destination cell is not allowed to be accessed.

[0165] Step 903: AMF sends an NG established response message to CU.

[0166] Step 904: CU sends an F1 established acknowledgment message to DU.

[0167] Step 905: CU (called CU1 to distinguish it from CU2) sends an Xn establishment request message to another CU (CU2).

[0168] CU1 needs to establish an interface with neighboring CU2. CU1 and CU2 are CUs of the NG RAN node. If they are CUs of an LTE base station, the message transmitted at this stage is an X2 establishment request message. That message carries information regarding the serving cell on CU1. The cell information includes unique identifiers of the cell, such as the Physical Cell Identifier (PCI) and Cell Global Identifier (CGI), and the cell operator identifier (e.g., PLMN ID). If the cell supports closed access groups, the cell information additionally includes a list of CAG identifiers. If the cell belongs to an SNPN, the cell information in the Xn establishment request message includes the PLMN identifier and the Network Identifier (NID).

[0169] Step 906: CU2 sends an Xn established acknowledgment message to CU1.

[0170] CU2 sends an Xn interface establishment response message to CU1, and the message carries information about the serving cell on CU2. The cell information includes a physical cell identifier (PCI), a unique identifier of the cell, such as a cell global identifier (CGI), and an operator identifier of the cell (e.g., PLMN ID). If the cell supports closed access groups, the cell information additionally includes a list of CAG identifiers. If the cell belongs to an SNPN, the cell information in the Xn establishment request message includes a PLMN identifier and a network identifier (NID).

[0171] FIG. 10 is a schematic diagram of a process in which a UE accesses a CAG cell according to one embodiment of the present disclosure. The base station is divided into a base station centralized control unit (CU) and a base station distribution unit (DU), where one DU may be connected to multiple CUs, and one CU may be connected to multiple DUs. The base station may be a 5G base station, an LTE base station, or a base station of another access mode. In this embodiment, a 5G base station is used as an example. If other systems are used, the corresponding interfaces and message names are changed accordingly. As illustrated in FIG. 10:

[0172] Step 1001: The UE sends an RRC establishment request message to the DU.

[0173] The UE initiates the establishment of an RRC connection and sends an RRC establishment request message to the DU. The message carries the UE's temporary identifier and the reason for the RRC establishment.

[0174] Step 1002: The DU sends an initial UL RRC message to the CU.

[0175] The DU sends an "initial UL RRC message delivery" to the CU via the F1 interface. The message name may be different. The message carries an RRC connection request message sent by the UE through the RRC container. The message also carries one or more of the following information.

[0176] The message also carries an identifier for F1 assigned to the UE by the DU.

[0177] The message also carries the cell global unique identifier (CGI) of the cell accessed by the UE. If the cell accessed by the UE supports a closed access group, the message additionally carries a list of CAG identifiers supported by the cell. If the cell accessed by the UE belongs to an SNPN, the message may additionally carry a PLMN identifier and a network identifier (NID).

[0178] The message also carries a Cell Radio Network Temporary Identifier (C-RNTI) assigned to the UE by the DU, which is a unique identifier used to identify the UE's RRC connection and scheduling.

[0179] The message also carries the RRC container from the DU to the CU, including cell group configuration information, which includes the necessary information required to establish SRB1.

[0180] The message also carries an RRC container containing RRC messages received from the UE by the DU.

[0181] Step 1003: CU sends a DL RRC message delivery to DU.

[0182] The CU sends a "DL RRC message delivery" to the DU via the F1 interface. The message name may be a different message name. The message carries one or more of the following information.

[0183] The message carries an identifier for F1 assigned to the UE by the CU.

[0184] The message carries a Signaling Radio Bearer (SRB) identifier. At this stage, the SRB identifier is set to SRB1.

[0185] The message carries an RRC container, and the RRC container contains an RRC establish message generated by the CU. The RRC establish message carries configuration information for SRB1. The RRC establish message is transmitted to the UE via the DU.

[0186] Step 1004: The DU sends a downlink RRC establishment message to the UE.

[0187] The DU sends the RRC establishment message received in step 1003 to the UE.

[0188] Step 1005: The UE sends an RRC establishment complete message to the DU.

[0189] The RRC connection establishment complete message carries the identifier of the operator selected by the UE (e.g., PLMN ID). The message also includes a non-access layer message. Upon receiving this message, the base station transmits the non-access layer message to the core network mobile function node (AMF).

[0190] Step 1006: DU sends the UL RRC message to CU.

[0191] The UL RRC message delivery carries the RRC establishment complete message received by the DU. After receiving the message of step 1005, the DU sends "UL RRC message delivery" to the CU via the F1 interface, and the message name may be a different message name.

[0192] Step 1007: CU sends an initial UE message to AMF.

[0193] After the CU receives the message of step 1006, the CU transmits an "Initial UE Message" to the AMF via the NG interface. This message carries the non-access layer message transmitted by the UE in step 1005. The message also carries the UE's location information, such as a unique identifier across the entire network of the cell to which the UE is located. If the cell accessed by the UE supports a closed access group, the message also carries a list of CAG identifiers supported by the cell. If the cell belongs to an SNPN, the Initial UE Message also includes a PLMN identifier and a Network Identifier (NID).

[0194] Step 1008: AMF sends an initial context establishment request message to CU.

[0195] Alternatively, the AMF receives the message of step 1007 and obtains the CAG identifier of the cell to which the UE is located, or the identifier of the CAG supported by the cell during the NG interface establishment process, and the CAG list stored by the AMF that the UE is allowed to access. By combining the above information, the AMF determines whether to allow the UE to access the serving cell. If the identifier of the CAG supported by the serving cell is not in the CAG list to allow the UE to access, or if the serving cell does not support CAG cells and only allows the UE to access CAG cells, the AMF determines that the UE is not allowed to access the serving cell, and the AMF may directly send a UE context release request message to the base station. That message may indicate the reason why access was denied, for example, that the reason for denial is that the cell is not allowed to be accessed. If access is allowed, the AMF sends an initial context establishment request message to the CU.

[0196] Alternatively, the AMF receives the message of step 1007 and knows the SNPN identifier of the cell to which the UE is located, or obtains the SNPN identifier supported by the cell during the NG interface establishment process. The AMF stores the UE's authentication information, which indicates which SNPNs can be accessed by the UE. Based on the above information, the AMF determines whether to allow the UE to access the serving cell. If the SNPN identifier supported by the serving cell is not in the list of SNPN identifiers to which the UE is allowed to access, the AMF determines that the UE is not allowed access to the serving cell, and the AMF may directly send a UE context release request message to the base station. The message may indicate the reason why access was denied, for example, that the reason for denial is that access is not allowed. If access is allowed, the AMF sends an initial context establishment request message to the CU.

[0197] Alternatively, the AMF sends an "initial context establishment request" message to the CU via the NG interface. The message name may be different. The message includes the identifier of the NG interface assigned to the UE by the AMF, the UE's radio capabilities, cryptographic capabilities, and information regarding the establishment of a data session (e.g., a PDU session), such as a data session identifier, quality requirements, etc. The message also carries a list of CAGs to allow the UE to access, and the message may also carry information regarding whether the UE is allowed to access only CAG cells.

[0198] Step 1009: The CU sends a request message to the DU to establish the UE context.

[0199] The context establishment request message carries an identifier for the UE's F1 and bearer information or PDU session information to be established. It also carries a list of CAGs that the UE is allowed to access, and the message may also carry instruction information regarding whether the UE is allowed to access only CAG cells. This information is stored in the DU, and the DU can use it as a basis for determining whether to allow the UE to access a specific cell. For example, when the UE is re-established in a cell under the DU, if the DU has the UE's context, the DU can determine whether the UE can access that cell based on the list of CAGs that the UE is allowed to access and the instruction information regarding whether the UE is allowed to access only CAG cells. Specific steps are described in the following process.

[0200] Step 1010: The DU sends a response to the CU establishing the UE context.

[0201] The context establishment request message carries the identifier for the UE's F1, the successfully established bearer information or PDU session information, and the unsuccessfully established bearer information or PDU session information. Subsequently, the process of establishing a bearer on the UE side by the CU is the same as the current process and is therefore omitted here.

[0202] Step 1011: CU sends an initial context establishment response message to AMF.

[0203] CU sends the response message of step 1008 to AMF.

[0204] FIG. 11 is a schematic diagram of a process in which a UE performs an Xn handover according to one embodiment of the present disclosure. The base station is divided into a base station centralized control unit (CU) and a base station distribution unit (DU), where one DU may be connected to multiple CUs, and one CU may be connected to multiple DUs. The base station may be a 5G base station, an LTE base station, or a base station of another access mode. In this embodiment, a 5G base station is used as an example. If other systems are used, the corresponding interfaces and message names are changed accordingly. As illustrated in FIG. 11:

[0205] Step 1101: The CU of the source base station sends a handover request message to the CU of the destination base station.

[0206] The CU of the source base station decides to transfer the UE to the destination base station based on the UE measurement results. If the destination base station is a cell not supported by a CAG, and the source base station knows the destination cell's CAG identifier from the Xn establishment process, and the UE is allowed to access only CAG cells, the source base station cannot transfer the UE to the destination base station. If the destination cell supports a CAG, but the identifier of the CAG supported by the destination cell is not in the list of CAGs to which the UE is allowed to access, the source base station cannot transfer the UE to the destination base station. The source base station sends a handover request message to the destination base station. The handover request message includes information about the destination base station and the destination cell. The message may also carry a list of CAGs that the UE is allowed to access, and the message may also carry information regarding whether the UE is allowed to access only CAG cells.

[0207] If the destination cell belongs to the SNPN and the SNPN identifier of the destination cell is the same as that of the source cell, and the source base station obtains the SNPN identifier of the cell on the destination base station from the Xn establishment process, the source base station may decide to initiate the handover of the Xn process. If the destination cell belongs to the SNPN but the SNPN identifier of the destination cell is different from that of the source cell, the source base station does not initiate the Xn handover but initiates the NG handover so that the AMF determines whether to allow the UE to switch to the destination cell / destination base station. The process of the NG handover is illustrated in FIG. 12. If the destination cell does not belong to the SNPN, the source base station does not initiate the handover procedure to the destination cell.

[0208] Step 1102: The CU of the destination base station sends a request message to establish UE context to the DU of the destination base station.

[0209] The context establishment request message carries an identifier for the UE's F1 and bearer information or PDU session information to be established. It also carries a list of CAGs that the UE is allowed to access, and the message may also carry instruction information regarding whether the UE is allowed to access only CAG cells. This information is stored in the DU, and the DU can use it as a basis for determining whether to allow the UE to access a specific cell.

[0210] Step 1103: The DU sends a response to the CU establishing the UE context.

[0211] The context establishment request message carries an identifier for the UE's F1, successfully established bearer information or PDU session information, and unsuccessfully established bearer information or PDU session information.

[0212] Step 1104: The destination base station CU sends a handover response message to the source base station CU.

[0213] The destination base station transmits a handover response message to the source base station. The message carries an identifier for the UE's Xn interface, bearer information or PDU session information accepted by the destination base station, and a handover command message to be sent to the UE.

[0214] Step 1105: The source base station CU sends a request to modify the UE context to the source base station DU.

[0215] In step 1105, the source base station CU transmits the handover command sent by the destination base station to the DU via a message.

[0216] Step 1106: The source base station DU transmits a handover command to the UE.

[0217] The source base station DU transmits the handover command transmitted by the destination base station to the UE.

[0218] Step 1107: The source base station DU sends a UE context modification response to the source base station CU.

[0219] Step 1108: The UE synchronizes with the destination cell and sends a handover completion message to the destination base station CU.

[0220] Step 1109: The destination base station CU sends the core network AMF in a route switching request message.

[0221] A route transition request message includes an identifier for the UE's NG interface, information about the bearer or PDU session to be transitioned, and the cell's unique cell identity. If the destination cell is a cell that supports CAG, the message may also carry the cell's CAG list. If the destination cell belongs to an SNPN, the message may also carry the cell's PLMN identifier and network identifier (NID).

[0222] Step 1110: The core network sends a route switching response message to the destination base station CU.

[0223] The route switching response message includes an identifier for the UE's NG interface, bearer information that was successfully switched, or PDU session information, and the switching response message includes a list of CAGs that the UE is allowed to access, and further includes instruction information regarding whether the UE is allowed to access only CAG cells.

[0224] In steps 1111 and 1112, the destination base station CU sends a UE context release request message to the source base station CU, and the source base station CU sends a UE context release request message to the source base station DU.

[0225] FIG. 12 is a schematic diagram of a process in which a UE performs an NG handover according to one embodiment of the present disclosure. In the current NG handover process, if the source base station and the destination base station belong to different local networks and the UE performs a core network-based handover process, the core network does not know the identifier of the local network supported by the destination base station until the UE switches to the destination base station, synchronizes with the destination cell, and transmits a handover completion message to the destination base station. Then, the destination base station transmits a handover notification message to the core network to notify the core network of the local network identifiers supported by itself in the handover notification message. At this time, the core network must release all bearers. As can be seen, data cannot be continuously transmitted when the current UE moves to a different local network, the core network does not know the local network identifier of the destination base station until the UE switches to the destination base station, and the release process is also delayed for a long time, so the UE unnecessarily establishes a connection with the destination cell. Therefore, this embodiment uses an optimized method to enable continuous data transmission and release bearers in advance, and the UE does not need to establish an unnecessary RRC connection. As shown in Fig. 12:

[0226] Step 1201: The source base station sends a handover request message to the AMF.

[0227] The CU of the source base station decides to transfer the UE to the destination base station based on the UE measurement results. The message carries the identifier of the destination base station or the identifier of the destination cell. The message may also carry the SNPN identifier of the destination cell. The message may carry the CAG identifier and / or SNPN identifier of the source cell, and may additionally carry the CAG identifier and / or SNPN identifier of the destination cell.

[0228] The source base station transmits a handover request message to the AMF via the NG interface in the following cases.

[0229] If there is an Xn interface between the source base station and the destination base station, the SNPN identifier of the cell on the destination base station is obtained from the Xn establishment process. If the destination cell belongs to the SNPN but the SNPN identifier of the destination cell is different from that of the source cell, even if there is an Xn interface, the source base station does not initiate an Xn handover but initiates an NG handover so that the AMF determines whether to allow the UE to switch to the destination cell / destination base station. If the SNPN identifier of the destination cell is the same as the SNPN identifier of the source cell, the source base station initiates the Xn handover process.

[0230] If there is no Xn interface between the source base station and the destination base station, the source base station obtains the identifier of the destination cell from the UE measurement report. Alternatively, the SNPN identifier of the destination cell may also be obtained. If the SNPN identifier of the destination cell is the same as the SNPN identifier of the source cell, the source base station transmits a handover request message of the NG interface to the AMF. In the handover request message, the source base station may carry instruction information, through which the source base station notifies the AMF that the destination cell and the source cell belong to the same SNPN.

[0231] If there is no Xn interface between the source base station and the destination base station, the source base station obtains the SNPN identifier of the destination cell from the UE measurement report. If the SNPN identifier of the destination cell is different from the SNPN identifier of the source cell, the source base station sends a handover request message for the NG interface to the AMF.

[0232] If there is no Xn interface between the source base station and the destination base station, the source base station does not know the SNPN identifier of the destination cell, and the source base station sends a handover request message of the NG interface to the AMF.

[0233] If there is no Xn interface between the source base station and the destination base station, the source base station obtains the identifier of the destination cell and the CAG identifier of the destination cell from the UE measurement report, and the source base station transmits a handover request message for the NG interface to the AMF.

[0234] Step 1202: The AMF sends a handover request to the destination base station.

[0235] The AMF receives the message of step 1201 and knows the SNPN identifier of the source cell and the SNPN identifier of the destination cell, or obtains the SNPN identifiers supported by the source cell and / or the destination cell during the NG interface establishment process. The AMF stores the UE's authentication information, which indicates which SNPNs can be accessed by the UE. Based on the above information, the AMF determines whether to allow the UE to access the destination cell. If the SNPN identifier supported by the destination cell is not in the list of SNPN identifiers to be accessed by the UE, the AMF determines that the UE is not allowed access to the destination cell, and the AMF may directly send a handover failure message to the source base station. The message may indicate the reason why access was denied, for example, that the reason for denial is that access is not allowed. If access is allowed, the AMF sends a handover request to the destination base station.

[0236] The AMF receives the message of step 1201 and knows the CAG identifier of the source cell and the CAG identifier of the destination cell, or obtains the CAG identifiers supported by the source cell and / or the destination cell during the NG interface establishment process. The AMF stores the UE's authentication information, which indicates which CAGs can be accessed by the UE. Based on the above information, the AMF determines whether to allow the UE to access the destination cell. If the CAG identifier supported by the destination cell is not in the list of CAG identifiers to which the UE is allowed to access, the AMF determines that the UE is not allowed access to the destination cell, and the AMF may directly send a handover failure message to the source base station. The message may indicate the reason why access was denied, for example, that the reason for denial is that access is not allowed. If access is allowed, the AMF sends a handover request to the destination base station.

[0237] The handover request message includes an identifier for the UE's NG interface and information regarding the PDU session to be established.

[0238] Step 1203: The destination base station transmits a handover response to the AMF.

[0239] The message carries an identifier for the UE's NG interface and information about the accepted PDU session. The message may also carry an identifier for the destination cell and an SNPN identifier for the destination cell. The message may also carry an identifier for the destination cell and a CAG identifier for the destination cell. The RRC container in the handover response message contains the handover command to be sent to the UE.

[0240] If the destination cell identifier and the destination cell SNPN identifier are included in step 1203, the AMF receives the message of step 1203 and knows the destination cell's SNPN identifier. The AMF stores the UE's authentication information, which indicates which SNPNs can be accessed by the UE. Based on the above information, the AMF determines whether to allow the UE to access the destination cell. If the SNPN identifier supported by the destination cell is not in the list of SNPN identifiers to allow the UE to access, the AMF determines that the UE is not allowed access to the destination cell, and the AMF may directly send a handover failure message to the source base station. The message may indicate the reason why access was denied, for example, that the reason for denial is that access is not allowed. If access is allowed, the AMF sends a handover request to the destination base station.

[0241] If the destination cell identifier and the destination cell CAG identifier are included in step 1203, the AMF receives the message of step 1203 and knows the destination cell's CAG identifier. The AMF stores the UE's authentication information, which indicates which CAGs can be accessed by the UE. Based on the above information, the AMF determines whether to allow the UE to access the destination cell. If the CAG identifier supported by the destination cell is not in the list of CAG identifiers allowed for the UE's access, the AMF determines that the UE is not allowed access to the destination cell, and the AMF may directly send a handover failure message to the source base station. The message may indicate the reason why access was denied, for example, that the reason for denial is that access is not allowed. If access is allowed, the AMF sends a handover request to the destination base station.

[0242] Step 1204: The AMF sends a handover command message to the source base station.

[0243] The message confirms that the destination base station is ready for handover. The message carries an identifier for the UE's NG interface and information about the PDU session accepted by the destination base station.

[0244] Step 1205: The source base station transmits a handover command to the UE.

[0245] The source base station transmits the handover command generated by the destination base station to the UE.

[0246] Step 1206: The UE synchronizes with the destination cell and sends a handover completion message to the destination base station.

[0247] Step 1207: The destination base station sends a handover notification message to the core network AMF.

[0248] FIG. 13 is a schematic diagram of a process according to one embodiment of the present disclosure in which a UE causes a wireless link failure in a previous cell, or the UE is in an RRC inactive mode, the UE moves to a new cell, initiates an RRC recovery process, and then the UE re-selects a new cell to initiate RRC re-establishment. The base station is separated into a base station centralized control unit (CU) and a base station distribution unit (DU), where one DU may be connected to multiple CUs, and one CU may be connected to multiple DUs. The base station may be a 5G base station, an LTE base station, or a base station of another access mode. In this embodiment, a 5G base station is used as an example. If other systems are used, the corresponding interfaces and message names are changed accordingly. FIG. 13 illustrates a process in which the UE re-selects a new cell to initiate RRC re-establishment after the UE causes a wireless link failure in a previous cell. If the base station is not separated, the CU and DU are on a single entity, and the procedure for transmitting messages between the CU and DU may be omitted. The CU / DU in the embodiments can be directly replaced by a base station. Alternatively, the new base station is the first base station, and the previous base station is the second base station. As illustrated in FIG. 13:

[0249] Step 1301: The UE sends an RRC re-establishment request message to the new DU.

[0250] After the UE performs cell reselection, the UE transmits an RRC re-establishment request message to the base station in the reselected cell. The RRC re-establishment request message includes the UE's re-establishment identifier. The UE's re-establishment identifier is used to locate the UE context and detect physical layer identifier conflicts. The UE's re-establishment identifier includes the UE's C-RNTI, which is the C-RNTI assigned by the previous cell. The physical cell identifier (PCI) of the cell prior to the UE's radio link failure—in other words, the previous cell identity—includes an authentication token (Short Mac-I) calculated by the UE. The RRC re-establishment request message includes the reason for the RRC reconnection. The reason for the RRC re-establishment can be a reset failure, a handover failure, etc.

[0251] When a UE in inactive mode initiates the RRC recovery process, the UE sends an RRC active request message to the new DU. The message includes the identifier of the UE from the previous cell. The identifier of the UE from the previous cell includes information about the previous base station, the C-RNTI assigned by the new cell, the physical cell identifier (PCI) of the new cell, and a unique identifier across the entire new network.

[0252] If the DU can parse an RRC message, the DU knows that the message is an RRC re-establishment message. Based on the UE's previous cell identity (PCI) and the UE's C-RNTI included in the message, the DU can determine whether the UE's previous cell is on the DU. If the UE's previous cell is on the DU, the DU can find the list of CAGs allowed for UE access and the indication information regarding whether the UE is allowed to access only CAG cells by locating the stored context information. If the cell receiving the UE re-establishment request supports CAGs but its CAG identifier is not on the list of CAGs allowed for UE access, or if the cell is not on a CAG cell and the above indication information indicates that the UE is allowed to access only CAGs, the DU can directly reject the RRC re-establishment message. An RRC release request is sent to the UE. The reason for the release is that the UE is not allowed to access.

[0253] If the DU can parse an RRC message, the DU knows that the message is an RRC recovery request message. Based on the UE's identifier from the previous cell included in the message, the DU can determine whether the UE's previous cell exists on the DU. If the previous cell exists on the DU, the DU can find the list of CAGs allowed for UE access and the indication information regarding whether the UE is allowed to access only CAG cells by locating the stored context information. If the cell receiving the UE recovery request supports CAGs but its CAG identifier is not in the list of CAGs allowed for UE access, or if the cell is not a CAG cell and the above indication information indicates that the UE is allowed to access only CAGs, the DU can directly reject the RRC re-establishment message. An RRC release request is sent to the UE. The reason for the release is that the UE is not allowed to access it.

[0254] Step 1302: The new DU sends an initial UL RRC message to the new CU, and the message carries an RRC re-establishment request message sent by the UE through an RRC container.

[0255] The DU transmits an "initial UL RRC message delivery" to the CU via the F1 interface, and the message name may be different. The message also carries one or more of the following information:

[0256] The message carries an identifier for F1 assigned to the UE by the DU.

[0257] The message carries the cell identity C-RNTI assigned to the UE by the DU. The C-RNTI is a unique identifier used to identify the UE's RRC connection and scheduling, and this is the new C-RNTI assigned to the UE by the DU.

[0258] The message carries the global unique identifier of the cell in the RRC message received by the DU, such as NG-CGI. The message also carries a container from the DU to the CU. The container from the DU to the CU contains cell group configuration information, which includes the information required to establish SRB1.

[0259] The message also carries an RRC container containing RRC messages received from the UE by the DU.

[0260] If the cell receiving the RRC re-establishment request message or the RRC recovery request message is a cell that supports CAG, the message may additionally carry the cell's CAG list. If the cell receiving the re-establishment request message or the RRC recovery request message belongs to an SNPN, the message may additionally carry the cell's PLMN identifier and network identifier (NID).

[0261] Step 1303: The new CU sends a request message to the previous CU to retrieve the UE context.

[0262] The new CU1 parses the RRC re-establishment request message. Based on the UE's re-establishment identifier included in the message, the new CU1 determines that the UE's context belongs to a different NG-RAN entity. When establishing Xn interfaces with other base stations, the CU obtains information about the serving cells of neighboring base stations; this serving cell information includes the cell's frequency, physical cell identifier (PCI), cell global unique identifier (NR-CGI), and the routing identifier of the cell TAC, so CU1 knows the physical cell identifier (PCI) for the other NG-RAN. Based on the PCI of the failed cell in the re-establishment identifier, the new CU1 determines that the UE context belongs to a different NG-RAN entity. The new CU sends a UE context extraction request message to the previous CU.

[0263] The new CU parses the RRC recovery request message. Based on the identifier of the UE from the previous cell included in the message, the identifier of the UE from the previous cell contains information from the previous base station NG-RAN, so the new CU1 can determine that the UE's context is for a different NG-RAN entity. The new CU (CU1) sends a UE context extraction request message to the previous CU (CU2).

[0264] The UE context extraction request message includes the UE context identifier. In the case of the RRC re-establishment process, the UE context identifier is the C-RNTI and PCI of the failed cell. The C-RNTI is the identifier assigned to the UE by the UE's serving cell before the wireless link failed. The message also includes the cell identity of the new cell. If the cell receiving the RRC connection request is a cell that supports CAG, the message may additionally carry the cell's CAG list. If the cell receiving the RRC connection request belongs to an SNPN, the message may additionally carry the cell's PLMN identifier and Network Identifier (NID).

[0265] In the case of the RRC recovery process, the UE context identifier includes the UE's identifier from the previous cell, the UE's temporary C-RNTI assigned by the new cell (i.e., the cell that received the RRC recovery request), and the new cell's PCI. The message also includes the new cell's unique cell identity, such as CGI, and the reason for the RRC recovery. The message also includes the new cell's cell identity. If the cell that received the RRC connection request is a cell that supports CAG, the message may also carry the cell's CAG list. If the cell that received the RRC connection request belongs to an SNPN, the message may also carry the cell's PLMN identifier and network identifier (NID).

[0266] Step 1304: The previous CU sends a UE context extraction failure message or a UE context extraction response message to the new CU.

[0267] The previous CU determines whether to transmit UE context information to the new CU based on the list of stored CAGs that the UE is allowed to access, and / or instruction information regarding whether the UE is allowed to access only CAG cells. If the new cell on the new CU (i.e., the cell for performing RRC re-establishment or RRC recovery) is a cell that does not support CAGs, and the previous cell can know the identifier of the CAG supported by the new cell from the Xn interface establishment process, or if, in step 1304, the identifier of the CAG supported by the new cell is known and the UE is allowed to access only CAG cells, the previous CU cannot transmit UE context information to the new CU. If the new cell supports CAGs, but the identifier of the CAG supported by the new cell is not in the list of CAGs that the UE is allowed to access, the previous CU cannot transmit UE context information to the CU where the new cell is located. The previous CU transmits a UE context extraction failure message to the new CU. The UE context extraction failure message includes the reason for the refusal, for example, that the reason for the refusal is that the cell is not allowed to be accessed.

[0268] If the previous cell belongs to SNPN and the new cell belongs to SNPN, but the SNPN identifier of the new cell is different from the SNPN identifier of the previous cell—in other words, if the two cells belong to different independent private networks—the previous CU cannot transmit UE context information to the new cell CU. The previous CU transmits a UE context extraction failure message to the new CU. The UE context extraction failure message includes the reason for the denial, for example, that access is not permitted. If the SNPN identifier of the new cell is the same as the SNPN identifier of the previous cell, the UE's context information can be transmitted to the new CU.

[0269] If the UE context can be transmitted to a new CU, the previous CU transmits a UE context extraction response message to the new CU, the UE context extraction response message containing the context information of the UE. The context information or the UE context extraction response message includes a list of CAGs that the UE is allowed to access, and instruction information regarding whether the UE is allowed to access only CAG cells.

[0270] Step 1305: The new CU sends a DL RRC message delivery to the new DU. The message name may be a different name or a newly defined message. The message carries an RRC release request message, or the message carries an RRC re-establishment response message, or the message carries an RRC recovery response message or an RRC recovery failure message.

[0271] If a UE context release failure message is received at step 1304, the CU sends an RRC release request message or an RRC active failure message to the UE. If a UE context release response message is received at step 1304, the CU sends an RRC re-establishment response or an RRC recovery response message to the UE. The message is first sent to the DU via a downlink RRC message through the F1 interface, and then sent to the UE by the DU.

[0272] Step 1306: The new DU sends an RRC release request or RRC re-establishment response message to the UE.

[0273] FIG. 14 is a schematic diagram of a process for establishing a dual connection according to one embodiment of the present disclosure. As illustrated in FIG. 14:

[0274] Step 1401: The primary base station transmits a secondary base station establishment request message to the secondary base station. The message carries a list of CAGs that the UE is allowed to access, and instructions regarding whether the UE is allowed to access only the CAG cells.

[0275] When a secondary base station selects a secondary cell, it must refer to the list of CAGs that the UE is allowed to access. If a cell is a CAG cell and its CAG identifier is not in the list of CAGs that the UE is allowed to access, that cell cannot be selected as a secondary cell. Alternatively, if the cell does not support CAGs and the UE can only access CAGs, then that cell cannot be selected as a secondary cell.

[0276] Step 1402: The secondary base station sends a secondary base station establishment response message to the primary base station.

[0277] Example 3

[0278] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure further provides a first base station. The structural diagram of the device is as shown in FIG. 15a. The first base station (150) includes a first processing module (1501), a second processing module (1502), a third processing module (1503), and a fourth processing module (1504).

[0279] The first processing module (1501) is configured to receive a wireless resource control (RRC) re-establishment request transmitted by a user device (UE);

[0280] The second processing module (1502) is configured to transmit a UE context extraction request to the second base station based on an RRC re-establishment request;

[0281] The third processing module (1503) is configured to receive a UE context extraction response message transmitted by the second base station, and the UE context extraction response message is determined by the second base station based on a first decision rule;

[0282] The fourth processing module (1504) is configured to send an RRC re-establishment response message to the UE to support the UE in accessing a closed network based on a UE context extraction response message, and the closed network includes at least one of a closed access group (CAG) and a self-supporting private network (SNPN).

[0283] Alternatively, the first decision rule includes at least one of the following:

[0284] The second base station determines whether the CAG supported by the cell of the first base station is in the list of CAG identifiers allowed by the UE, and if so, a UE context extraction response message is transmitted to the first base station, and if not, a UE context extraction failure message is transmitted to the first base station;

[0285] The second base station determines whether the SNPN identifier for the cell of the first base station is the same as the SNPN identifier for the cell of the second base station, and if so, a UE context extraction response message is transmitted to the first base station, and if not, a UE context extraction failure message is transmitted to the first base station.

[0286] Where there are details not described in detail in the first base station provided in the embodiments of the present disclosure, the aforementioned method for supporting access to a closed network may be referenced. The beneficial effects that can be achieved by the first base station provided in the embodiments of the present disclosure are the same as those achieved by the method described above for supporting access to a closed network, and are not repeated herein.

[0287] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0288] Example 4

[0289] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure further provides a second base station. The structure of the device is as shown in FIG. 15b. The second base station (151) includes a reception request module (1511) and a message transmission module (1512).

[0290] The reception request module (1511) is configured to receive a UE context extraction request transmitted by the first base station; and

[0291] The message transmission module (1512) is configured to transmit a UE context extraction response message to the first base station, the UE context extraction response message is determined based on a first determination rule to support the UE in accessing a closed network, and the closed network includes at least one of a closed access group (CAG) and a self-contained private network (SNPN).

[0292] Alternatively, the first decision rule includes at least one of the following:

[0293] The second base station determines whether the CAG supported by the cell of the first base station is in the list of CAG identifiers allowed by the UE, and if so, a UE context extraction response message is transmitted to the first base station, and if not, a UE context extraction failure message is transmitted to the first base station;

[0294] The second base station determines whether the SNPN identifier for the cell of the first base station is the same as the SNPN identifier for the cell of the second base station, and if so, a UE context extraction response message is transmitted to the first base station, and if not, a UE context extraction failure message is transmitted to the first base station.

[0295] Where there are details not described in detail in the second base station provided in the embodiments of the present disclosure, the aforementioned method for supporting access to a closed network may be referenced. The beneficial effects that can be achieved by the second base station provided in the embodiments of the present disclosure are the same as those achieved by the method described above for supporting access to a closed network, and are not repeated herein.

[0296] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0297] Example 5

[0298] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure further provides a UE. The structural diagram of the device is as shown in FIG. 16. The UE (160) includes a fifth processing module (1601), a sixth processing module (1602), and an access processing module (1603).

[0299] The fifth processing module (1601) is configured to transmit an RRC re-establishment request to the first base station;

[0300] The sixth processing module (1602) is configured to receive an RRC re-establishment response message transmitted by the first base station;

[0301] The access processing module (1603) is configured to access a closed network, and the closed network includes at least one of a closed access group (CAG) and a self-contained private network (SNPN).

[0302] Where there are details not described in detail in the UE provided in the embodiments of the present disclosure, the aforementioned method for supporting access to a closed network may be referenced. The beneficial effects that can be achieved by the UE provided in the embodiments of the present disclosure are the same as those achieved by the method described above for supporting access to a closed network, and are not repeated herein.

[0303] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0304] Example 6

[0305] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure also provides a first CU. The structural diagram of the device is as shown in FIG. 17. The first CU (170) includes a seventh processing module (1701), an eighth processing module (1702), a ninth processing module (1703), a tenth processing module (1704), an eleventh processing module (1705), and a twelfth processing module (1706).

[0306] The seventh processing module (1701) is configured to receive an F1 establishment request transmitted by a distribution unit (DU), and the F1 establishment request includes at least one of a list of closed access group (CAG) identifiers and a self-supporting private network (SNPN) identifier;

[0307] The eighth processing module (1702) is configured to transmit an NG establishment request to the Access and Mobility Management Function (AMF) of the core network, and the NG establishment request includes at least one of a list of CAG identifiers and an SNPN identifier;

[0308] The ninth processing module (1703) is configured to receive an NG establishment response transmitted by the AMF;

[0309] The 10th processing module (1704) is configured to transmit an F1 established response to the DU;

[0310] The 11th processing module (1705) is configured to transmit an Xn establishment request to the 2nd CU, the Xn establishment request includes at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN;

[0311] The 12th processing module (1706) is configured to receive an Xn establishment response transmitted by the 2nd CU, the Xn establishment response includes at least one of a list of CAG identifiers and / or SNPN identifiers to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN.

[0312] Alternatively, when the F1 establishment request includes a list of CAG identifiers, the information carried by the NG establishment request includes at least one of the following:

[0313] Information regarding a base station identifier, a base station routing area, a base station operator identifier, a list of CAG identifiers supported by the base station, and cells supported by the base station, wherein the information regarding cells supported by the base station includes a cell identity, a cell operator identifier, a cell routing area identifier, and a list of CAG identifiers supported by the cell.

[0314] Alternatively, when the F1 establishment request includes an SNPN identifier, the information carried by the NG establishment request includes at least one of the following:

[0315] Public Land Mobility Network (PLMN) identifier and Network Identifier (NID).

[0316] Where there are details not described in detail in the first CU provided in the embodiments of the present disclosure, the aforementioned method for supporting access to a closed network may be referenced. The beneficial effects that can be achieved by the first CU provided in the embodiments of the present disclosure are the same as those achieved by the method described above for supporting access to a closed network, and are not repeated herein.

[0317] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0318] Example 7

[0319] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure also provides a CU. The structure of the device is as shown in FIG. 18, and the CU (180) includes a receiving processing module (1801), a 13th processing module (1802), a 14th processing module (1803), a 15th processing module (1804), a 16th processing module (1805), a 17th processing module (1806), an 18th processing module (1807), and a 19th processing module (1808).

[0320] The receiving processing module (1801) is configured to receive an initial UL RRC message transmitted by the DU;

[0321] The 13th processing module (1802) is configured to transmit a DL RRC message to the DU;

[0322] The 14th processing module (1803) is configured to receive UL RRC message transmissions sent by the DU;

[0323] The 15th processing module (1804) is configured to transmit an initial UE message to the AMF, the initial UE message comprising at least one of a cell global unique identifier of the cell to which the UE is located, a list of CAG identifiers supported by the cell, a PLMN identifier, and an NID;

[0324] The 16th processing module (1805) is configured to receive an initial context establishment request message transmitted by the AMF;

[0325] The 17th processing module (1806) is configured to send a UE context establishment request message to the DU, and the UE context establishment request message includes at least one of a list of CAG identifiers that the UE is allowed to access and instruction information for indicating whether the UE is allowed to access only CAG cells;

[0326] The 18th processing module (1807) is configured to receive a UE context establishment response transmitted by the DU;

[0327] The 19th processing module (1808) is configured to send an initial context establishment response message to the AMF to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN.

[0328] Alternatively, the initial UL RRC message delivery includes at least one of the following:

[0329] Identifier for F1 assigned by DU to the UE;

[0330] Cell global identifier (CGI) of a cell accessed by the UE;

[0331] If the cell accessed by the UE supports CAG, the initial UL RRC message delivery additionally carries a list of CAG identifiers supported by that cell;

[0332] If the cell accessed by the UE belongs to an SNPN, the initial UL RRC message delivery additionally carries a PLMN identifier and an NID;

[0333] It is a Cell Radio Network Temporary Identifier (C-RNTI) assigned to the UE by the DU, and the C-RNTI is a unique identifier used to identify the UE's RRC connection and scheduling;

[0334] It is an RRC container from DU to CU, and the RRC container contains cell group configuration information containing information required to establish SRB1.

[0335] Alternatively, the initial context establishment request message includes at least one of the following:

[0336] Identifier of the NG interface assigned to the UE by the AMF, the UE's radio capability, the UE's encryption capability, information related to the establishment of a data session, a list of CAG identifiers allowed to be accessed by the UE, and indication information indicating whether the UE is allowed to access only the CAG cell.

[0337] Where there are details not described in detail in the CU provided in the embodiments of the present disclosure, the aforementioned method for supporting access to a closed network may be referenced. The beneficial effects achieved by the CU provided in the embodiments of the present disclosure are the same as those achieved by the above method for supporting access to a closed network, and are not repeated herein.

[0338] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0339] Example 8

[0340] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure also provides a destination base station. The structure of the device is as shown in FIG. 19. The destination base station (190) includes a 20th processing module (1901), a 21st processing module (1902), a 22nd processing module (1903), a 23rd processing module (1904), and a 24th processing module (1905).

[0341] The 20th processing module (1901) is configured to receive a handover request message transmitted by a source base station, and the handover request message includes at least one of information of a destination base station, information of a destination cell, a list of CAG identifiers that the UE is allowed to access, and instruction information for indicating whether the UE is allowed to access only the CAG cell;

[0342] The 21st processing module (1902) is configured to transmit a handover response message to the source base station;

[0343] The 22nd processing module (1903) is configured to receive a handover completion message for a UE switching from a source base station to a destination base station;

[0344] The 23rd processing module (1904) is configured to send a route switching request message to the AMF, and the route switching request message includes at least one of a list of CAG identifiers for a cell, a PLMN identifier for a cell, and an NID;

[0345] The 24th processing module (1905) is configured to receive a route switching response message transmitted by the AMF, the route switching response message includes at least one of a list of CAG identifiers that the UE is allowed to access to support the UE in accessing a closed network and instruction information for indicating whether the UE is allowed to access only a CAG cell, and the closed network includes at least one of a CAG and an SNPN.

[0346] Where there are details not described in detail in the destination base station provided in the embodiments of the present disclosure, the above method for supporting access to a closed network may be referenced. The beneficial effects provided by the destination base station provided in the embodiments of the present disclosure are the same as those achieved by the above method for supporting access to a closed network, and are not repeated herein.

[0347] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0348] Example 9

[0349] Based on the same inventive concepts of the first and second embodiments above, this embodiment of the present disclosure further provides a primary base station. The structure of the device is as shown in FIG. 20. The primary base station (200) includes a 25th processing module (2001) and a 26th processing module (2002).

[0350] The 25th processing module (2001) is configured to transmit a secondary base station establishment request message to a secondary base station, and the secondary base station establishment request message includes at least one of a list of CAG identifiers that the UE is allowed to access and instruction information for indicating whether the UE is allowed to access only the CAG cell;

[0351] The 26th processing module (2002) is configured to receive a secondary base station establishment response message transmitted by a secondary base station to support the UE in accessing a closed network, and the closed network includes at least one of a CAG and an SNPN.

[0352] Where there are details not described in detail in the primary base station provided in this embodiment of the present disclosure, the above method for supporting access to a closed network may be referenced. The beneficial effects provided by the primary base station provided in the embodiment of the present disclosure are the same as those achieved by the above method for supporting access to a closed network, and are not repeated herein.

[0353] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0354] Example 10

[0355] Based on the same inventive concepts of the first and second embodiments above, embodiments of the present disclosure provide a computer-readable storage medium storing a computer program that implements a method for supporting access to a closed network according to either embodiment 1 and 2 when executed by a processor.

[0356] The computer-readable storage media provided in the embodiments of the present disclosure include, without limitation, any type of disk (including floppy disks, hard disks, optical disks, CD-ROMs, and magneto-optical disks), read-only memory (ROM), and random access memory (RAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash, magnetic cards, or optical cards. In other words, the readable storage media includes any medium that stores or transmits information in a readable form by a device (e.g., a computer).

[0357] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0358] Example 11

[0359] FIG. 21 schematically illustrates a structural block diagram of a base station or base station CU or base station DU performing the method of the present disclosure according to one embodiment of the present disclosure. As illustrated in FIG. 21, the base station CU (2100) or base station DU (2100) comprises: a communication interface (2101) for external communication; a processing unit or processor (2102) which may be a single unit or a combination of multiple units for performing different steps of a method supporting access to a closed network; and a memory (2103) storing computer-executable instructions that, when executed by the processor (2102), cause a primary base station or a secondary base station to perform embodiments of the present disclosure. However, not all of the illustrated components are essential. The base station CU (2100) or base station DU (2100) may be implemented by more or fewer components than those illustrated in FIG. 21.

[0360] The communication interface (2101) may include a transceiver. The transceiver (2220) may include an RF transmitter that up-converts and amplifies a transmitted signal, and an RF receiver that down-converts the frequency of a received signal. However, according to other embodiments, the transceiver may be implemented by more or fewer components than those exemplified in the components.

[0361] A communication interface (2101) is connected to a processor (2102) and can transmit and / or receive signals. The signals may include control information and data. Additionally, the communication interface (2101) can receive signals via a wireless channel and output the signals to the processor (2102). The communication interface (2101) can transmit signals output from the processor (2102) via a wireless channel.

[0362] The processor (2102) may include one or more processors or other processing devices that control the proposed function, process and / or method. The operation of the base station CU (2100) or base station DU (2100) may be implemented by the processor (2102).

[0363] When commands are executed by the processor (2102), if the CU shown in FIG. 21 is new, the primary base station (2100) performs the following operations: the operation of transmitting a UE context extraction request message to the previous CU through the communication interface (2101), wherein the message carries the identity of the new cell and also carries a CAG identifier or SNPN identifier supported by the cell; the operation of receiving a response message from the previous CU through the communication interface (2101); and the operation of transmitting an RRC message to the UE based on the response information.

[0364] Alternatively, a UE context extraction request includes one or more of the following information:

[0365] UE context identifiers C-RNTI and PCI of the failed cell;

[0366] The identity of the new cell accessed by the UE; and

[0367] CAG identifier or SNPN identifier supported by the cell.

[0368] Alternatively, the UE context extraction failure message includes the reason for the failure.

[0369] The processor (2102) may be a single central processing unit (CPU), but may also include two or more processing units. Alternatively, the processor may include a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)). The processor may also include on-board memory for caching use. A computer program may be executed by a computer program product connected to the processor. The computer program product may include a computer-readable medium that stores the computer program. For example, the computer program product may be flash memory, random access memory (RAM), read-only memory (ROM), and EEPROM; in an alternative embodiment, the computer program module may be distributed among different computer program products in the form of memory in the UE.

[0370] The embodiments of the present disclosure have the advantage of enabling at least users of a closed access group (CAG) or users belonging to a self-contained private network (SNPN) to access the said CAG cell or SNPN cell.

[0371] It should be understood by a person skilled in the art that each block in structured block graphs and / or block graphs and / or flowcharts, as well as combinations of such blocks, can be implemented through computer program instructions. It should be understood by a person skilled in the art that these computer program instructions can be provided to create machines on general-purpose computers, dedicated computers, or other processors capable of programming data processing methods, in order to implement the methods specified in the block(s) of structured block graphs and / or block graphs and / or flowcharts through instructions executed on computers or other processors capable of programming data processing methods.

[0372] It should be understood by those skilled in the art that the various operations, methods, flow steps, measures, and schemes discussed in this disclosure may be replaced, modified, combined, or deleted. Furthermore, other operations, methods, flow steps, measures, and schemes involving the various operations, methods, flow steps, measures, and schemes discussed in this disclosure may also be replaced, modified, rearranged, decomposed, combined, or deleted. Furthermore, other operations, methods, flow steps, measures, and schemes having the same functions as the various operations, methods, flow steps, measures, and schemes discussed in this disclosure may also be replaced, modified, rearranged, decomposed, combined, or deleted.

[0373] The above description is merely a part of the embodiments of the present disclosure. To those skilled in the art, various improvements and modifications may be made without departing from the principles of the present disclosure. Such improvements and modifications should also be considered within the scope of protection of the present disclosure.

Claims

Claim 1 A method in which a base station in a wireless communication system supports a non-public network (NPN) comprises: transmitting an initial UE (user equipment) message containing a list of CAG (closed access group) identifiers to an AMF (access and mobility management function); receiving an initial context setup request message from the AMF containing access permission information for CAG cells; transmitting a handover request message containing the access permission information to a target base station; and receiving a handover request response message from the target base station, wherein the access permission information includes a list of allowed CAGs and information on whether a UE is allowed to access non-CAG cells. Claim 2 A method according to claim 1, further comprising the step of deciding not to hand over the UE to the target cell based on the fact that the target cell is a CAG cell and the CAG identifier supported by the target cell is not included in the allowed CAG list. Claim 3 A method according to claim 1, further comprising the step of deciding not to hand over the UE to the target cell based on the fact that the target cell is a non-CAG cell and the UE is allowed to access only CAG cells. Claim 4 delete Claim 5 A method according to claim 1, wherein the handover request response message includes a handover command message. Claim 6 delete Claim 7 A base station supporting a non-public network (NPN) in a wireless communication system comprises: a transceiver; and at least one processor, wherein the at least one processor transmits an initial UE (user equipment) message containing a list of CAG (closed access group) identifiers to an AMF (access and mobility management function), receives an initial context setup request message from the AMF containing access permission information for CAG cells, transmits a handover request message containing the access permission information to a target base station, and receives a handover request response message from the target base station, wherein the access permission information includes an allowed CAG list and information on whether a UE is allowed to access non-CAG cells. Claim 8 In claim 7, the base station, wherein at least one processor determines not to hand over the UE to the target cell based on the fact that the target cell is a CAG cell and the CAG identifier supported by the target cell is not included in the allowed CAG list. Claim 9 In claim 7, the base station, wherein at least one processor determines not to hand over the UE to the target cell based on the fact that the target cell is a non-CAG cell and the UE is allowed to access only CAG cells. Claim 10 delete Claim 11 In paragraph 7, the base station, wherein the handover request response message includes a handover command message. Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete

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