Method, apparatus and computer program

Abstract

There is provided a method performed by a radio access network, RAN, node, wherein the method comprises storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node The method further comprises providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

Description

METHOD, APPARATUS AND COMPUTER PROGRAMCross-Reference To Related Applications

[0001] This patent application claims the benefit of priority of Indian Patent Application No. 202441010943, filed February 16, 2024, which is hereby incorporated by reference as if reproduced in its entirety.Technical Field

[0002] Various examples of this disclosure relate to methods, apparatuses, and computer programs for a communication network.Background

[0003] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

[0004] Such communication networks operate in accordance with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP.Summary

[0005] Some examples of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described below.

[0006] According to an aspect, there is provided a method performed by a radio access network, RAN, node, the method comprising: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RANnode; and providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0007] In some examples, the providing information related to the data record comprises: providing, to the core network node, the data record.

[0008] In some examples, the storing of the at least one neighbour group identity in the data record is based on the TA that is related to the at least one neighbour group identity, and wherein the at least one neighbour group identity is associated with the TA within the data record.

[0009] In some examples, the information related to the data record is provided, to the core network node, per TA supported by the RAN node.

[0010] In some examples, the data record is arranged to include neighbour group identities per TA supported by the RAN node.

[0011] In some examples, the method comprises: storing, in the data record, for the TA that is supported by the RAN node, a home group identity, wherein the home group identity comprises a group identity that is supported in a cell of the TA.

[0012] In some examples, for each group identity comprised in the data record, an indication of an associated TA is stored in the data record.

[0013] In some examples, the TA that is associated with a group identity is used as an index for storing the respective group identity in the data record.

[0014] In some examples, a neighbour group identify of the at least one neighbour group identity comprises a respective one of the following: an identity for a closed subscriber group, or an identity for a closed access group.

[0015] In some examples, the determining comprises: receiving, from a user equipment in a first cell of the TA, a message comprising the at least one neighbour group identity, wherein the at least one neighbour group identity is associated with a second cell that neighbours the first cell of the TA; and storing, in the data record, the at least one neighbour group identity based on the TA.

[0016] In some examples, the determining comprises: receiving, from an operations and maintenance entity, data related to the data record, wherein the data comprises the at least one neighbour group identity; and determining the data record based on the data.

[0017] In some examples, the method further comprises: receiving, from a further user equipment in a third cell of a further TA supported by the RAN node, a further message comprising a further neighbour group identity that is associated with a fourth cell thatneighbours the third cell of the further TA; and storing, in the data record, the further neighbour group identity based on the further TA.

[0018] In some examples, at least one of the message, or the further message, is a radio resource control, RRC, message.

[0019] In some examples, the method comprises: providing, by the RAN node to at least one user equipment, a trigger for a measurement report; and receiving, based on the providing of the trigger, at least one measurement report within an RRC message, the RRC message comprising at least one of: the at least one neighbour group identity or the further neighbour group identity.

[0020] In some examples, the trigger is associated with an automatic neighbour relationship process.

[0021] In some examples, the at least one measurement report is associated with mobility of the at least one user equipment.

[0022] In some examples, the providing comprises: providing, to the core network node, a next generation application protocol, NGAP, message comprising the information related to the data record.

[0023] In some examples, the NGAP message is at least one of: a RAN configuration update message, or an NG setup request message.

[0024] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0025] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0026] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0027] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0028] According to an aspect, there is provided an apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0029] In some examples, the providing information related to the data record comprises: providing, to the core network node, the data record.

[0030] In some examples, the storing of the at least one neighbour group identity in the data record is based on the TA that is related to the at least one neighbour group identity, and wherein the at least one neighbour group identity is associated with the TA within the data record.

[0031] In some examples, the information related to the data record is provided, to the core network node, per TA supported by the RAN node.

[0032] In some examples, the data record is arranged to include neighbour group identities per TA supported by the RAN node.

[0033] In some examples, the apparatus is caused to perform: storing, in the data record, for the TA that is supported by the RAN node, a home group identity, wherein the home group identity comprises a group identity that is supported in a cell of the TA.

[0034] In some examples, for each group identity comprised in the data record, an indication of an associated TA is stored in the data record.

[0035] In some examples, the TA that is associated with a group identity is used as an index for storing the respective group identity in the data record.

[0036] In some examples, a neighbour group identify of the at least one neighbour group identity comprises a respective one of the following: an identity for a closed subscriber group, or an identity for a closed access group.

[0037] In some examples, the determining comprises: receiving, from a user equipment in a first cell of the TA, a message comprising the at least one neighbour group identity, wherein the at least one neighbour group identity is associated with a second cell that neighbours the first cell of the TA; and storing, in the data record, the at least one neighbour group identity based on the TA.

[0038] In some examples, the determining comprises: receiving, from an operations and maintenance entity, data related to the data record, wherein the data comprises the at least one neighbour group identity; and determining the data record based on the data.

[0039] In some examples, the apparatus is caused to perform: receiving, from a further user equipment in a third cell of a further TA supported by the RAN node, a further message comprising a further neighbour group identity that is associated with a fourth cell that neighbours the third cell of the further TA; and storing, in the data record, the further neighbour group identity based on the further TA.

[0040] In some examples, at least one of the message, or the further message, is a radio resource control, RRC, message.

[0041] In some examples, the apparatus is caused to perform: providing, by the RAN node to at least one user equipment, a trigger for a measurement report; and receiving, based on the providing of the trigger, at least one measurement report within an RRC message, the RRC message comprising at least one of: the at least one neighbour group identity or the further neighbour group identity.

[0042] In some examples, the trigger is associated with an automatic neighbour relationship process.

[0043] In some examples, the at least one measurement report is associated with mobility of the at least one user equipment.

[0044] In some examples, the providing comprises: providing, to the core network node, a next generation application protocol, NGAP, message comprising the information related to the data record.

[0045] In some examples, the NGAP message is at least one of: a RAN configuration update message, or an NG setup request message.

[0046] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0047] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0048] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0049] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0050] According to an aspect, there is provided an apparatus comprising means for: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0051] In some examples, the providing information related to the data record comprises: providing, to the core network node, the data record.

[0052] In some examples, the storing of the at least one neighbour group identity in the data record is based on the TA that is related to the at least one neighbour group identity, and wherein the at least one neighbour group identity is associated with the TA within the data record.

[0053] In some examples, the information related to the data record is provided, to the core network node, per TA supported by the RAN node.

[0054] In some examples, the data record is arranged to include neighbour group identities per TA supported by the RAN node.

[0055] In some examples, the means are for: storing, in the data record, for the TA that is supported by the RAN node, a home group identity, wherein the home group identity comprises a group identity that is supported in a cell of the TA.

[0056] In some examples, for each group identity comprised in the data record, an indication of an associated TA is stored in the data record.

[0057] In some examples, the TA that is associated with a group identity is used as an index for storing the respective group identity in the data record.

[0058] In some examples, a neighbour group identify of the at least one neighbour group identity comprises a respective one of the following: an identity for a closed subscriber group, or an identity for a closed access group.

[0059] In some examples, the determining comprises: receiving, from a user equipment in a first cell of the TA, a message comprising the at least one neighbour group identity, wherein the at least one neighbour group identity is associated with a second cell that neighbours the first cell of the TA; and storing, in the data record, the at least one neighbour group identity based on the TA.

[0060] In some examples, the determining comprises: receiving, from an operations and maintenance entity, data related to the data record, wherein the data comprises the at least one neighbour group identity; and determining the data record based on the data.

[0061] In some examples, the means are for: receiving, from a further user equipment in a third cell of a further TA supported by the RAN node, a further message comprising a further neighbour group identity that is associated with a fourth cell that neighbours the third cell of the further TA; and storing, in the data record, the further neighbour group identity based on the further TA.

[0062] In some examples, at least one of the message, or the further message, is a radio resource control, RRC, message.

[0063] In some examples, the means are for: providing, by the RAN node to at least one user equipment, a trigger for a measurement report; and receiving, based on the providing of the trigger, at least one measurement report within an RRC message, the RRC message comprising at least one of: the at least one neighbour group identity or the further neighbour group identity.

[0064] In some examples, the trigger is associated with an automatic neighbour relationship process.

[0065] In some examples, the at least one measurement report is associated with mobility of the at least one user equipment.

[0066] In some examples, the providing comprises: providing, to the core network node, a next generation application protocol, NGAP, message comprising the information related to the data record.

[0067] In some examples, the NGAP message is at least one of: a RAN configuration update message, or an NG setup request message.

[0068] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0069] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0070] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0071] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0072] In some examples, the apparatus is the RAN node.

[0073] According to an aspect, there is provided an apparatus comprising: circuitry configured to perform: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and circuitry configured to perform: providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0074] According to an aspect, there is provided a computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA,supported by the RAN node; and providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0075] According to an aspect, there is provided a method performed by a core network node, the method comprising: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0076] In some examples, the information related to the data record that is associated with the RAN node further comprises at least one home group identity, wherein a respective home group identity of the at least one home group identity comprises a group identity that is supported in a cell of the TA supported by the RAN node, and wherein the storing of the data further comprises: for the TA, storing the at least one home group identity.

[0077] In some examples, the method is comprising: receiving, from a user equipment, a registration request message; in response to the registration request message, determining a registration area, RA, for the user equipment; identifying, using the data that has been stored, for each TA of the RA, at least one group identity which is either: a home group identity of the TA, or a neighbour group identity of the TA; filtering a list of group identities that are permitted to be accessed by the user equipment based on the identifying, so to obtain a filtered list of group identities; and providing, to the user equipment, the filtered list of group identities.

[0078] In some examples, the method is further comprising providing, to the RAN node, the filtered list of group identities.

[0079] In some examples, the filtering comprises: obtaining the list of group identities associated with the user equipment; and removing, from the list of group identities, group identities that are not identified as either: a home group identity of the TA, or a neighbour group identity of the TA.

[0080] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0081] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0082] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0083] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0084] According to an aspect, there is provided an apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0085] In some examples, the information related to the data record that is associated with the RAN node further comprises at least one home group identity, wherein a respective home group identity of the at least one home group identity comprises a group identity that is supported in a cell of the TA supported by the RAN node, and wherein the storing of the data further comprises: for the TA, storing the at least one home group identity.

[0086] In some examples, the apparatus is caused to perform: receiving, from a user equipment, a registration request message; in response to the registration request message, determining a registration area, RA, for the user equipment; identifying, using the data that has been stored, for each TA of the RA, at least one group identity which is either: a home group identity of the TA, or a neighbour group identity of the TA; filtering a list of group identities that are permitted to be accessed by the user equipment based on the identifying, so to obtain a filtered list of group identities; and providing, to the user equipment, the filtered list of group identities.

[0087] In some examples, the apparatus is caused to perform: providing, to the RAN node, the filtered list of group identities.

[0088] In some examples, the filtering comprises: obtaining the list of group identities associated with the user equipment; and removing, from the list of group identities, group identities that are not identified as either: a home group identity of the TA, or a neighbour group identity of the TA.

[0089] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0090] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0091] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0092] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0093] In some examples, the apparatus is a core network node.

[0094] According to an aspect, there is provided an apparatus comprising means for: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0095] In some examples, the information related to the data record that is associated with the RAN node further comprises at least one home group identity, wherein a respective home group identity of the at least one home group identity comprises a group identity that is supported in a cell of the TA supported by the RAN node, and wherein the storing of the data further comprises: for the TA, storing the at least one home group identity.

[0096] In some examples, the means are for: receiving, from a user equipment, a registration request message; in response to the registration request message, determining a registration area, RA, for the user equipment; identifying, using the data that has been stored, for each TA of the RA, at least one group identity which is either: a home group identity of the TA, or a neighbour group identity of the TA; filtering a list of group identities that are permitted to be accessed by the user equipment based on the identifying, so to obtain a filtered list of group identities; and providing, to the user equipment, the filtered list of group identities.

[0097] In some examples, the means are for: providing, to the RAN node, the filtered list of group identities.

[0098] In some examples, the filtering comprises: obtaining the list of group identities associated with the user equipment; and removing, from the list of group identities, group identities that are not identified as either: a home group identity of the TA, or a neighbour group identity of the TA.

[0099] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0100] In some examples, the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

[0101] In some examples, the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

[0102] In some examples, the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

[0103] In some examples, the apparatus is a core network node.

[0104] According to an aspect, there is provided an apparatus comprising: circuitry configured to perform: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and circuitry configured to perform: storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0105] According to an aspect, there is provided a computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0106] According to an aspect, there is provided a system comprising: a radio access network, RAN, node; and a core network node, wherein the RAN node comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the RAN node to perform: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to the core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity, and wherein the core network node comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the core network node to perform: receiving, from the radio access network, RAN, node, information related to the data record that is associated with the RAN node, wherein the information comprises the at least one neighbour groupidentity; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0107] According to an aspect, there is provided a system comprising: a radio access network, RAN, node; and a core network node, wherein the RAN node comprises means for: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to the core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity, and wherein the core network node comprises means for: receiving, from the radio access network, RAN, node, information related to the data record that is associated with the RAN node, wherein the information comprises the at least one neighbour group identity; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0108] A computer product stored on a medium may cause an apparatus to perform the methods as described herein.

[0109] A non-transitory computer readable medium comprising program instructions, that, when executed by an apparatus, cause the apparatus to perform the methods as described herein.

[0110] An electronic device may comprise apparatus as described herein.[OHl] Various other aspects and further embodiments are also described in the following detailed description and in the attached claims.

[0112] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure.

[0113] List of Abbreviations:AF: Application FunctionAMF: Access and Mobility Management FunctionAN: Access NetworkANR: Automatic neighbour relationBS: Base StationCAG: Closed access groupCSG: Closed subscriber groupCN: Core NetworkDL: Downlink eNB: eNodeB gNB: gNodeBHeNB: Home eNBHgNB: Home gNBHO: HandoverHSS: Home subscriber serverIIoT : Industrial Internet of ThingsLTE: Long Term EvolutionMME: Mobility management entityMS: Mobile StationMRL: Mobility restriction listNEF : Network Exposure FunctionNG-RAN: Next Generation Radio Access NetworkNF : N etwork F uncti onNR: New RadioNRF : Network Repository FunctionNW: NetworkPCF Policy Control FunctionPLMN: Public Land Mobile NetworkPGW : Packet data network gatewayPGW-C: Packet data network gateway control planePNI-NPN : Public Network Integrated Non-Public NetworkRA: Registration areaRAN: Radio Access NetworkRAT : Radio access technologyRF: Radio FrequencySMF : Session Management FunctionTA: Tracking areaTAC: Tracking area codeUE: User EquipmentUDR: Unified Data RepositoryUDM: Unified Data ManagementUL: UplinkUPF : User Plane Function3 GPP: 3rdGeneration Partnership Project5G: 5thGeneration5GC: 5G Core network5G-AN: 5G Radio Access Network5GS: 5G SystemBrief Description of Drawings

[0114] Some examples will now be described, by way of illustrative and non-limiting example only, with reference to the accompanying drawings in which:

[0115] FIG. 1 shows a schematic representation of a 5G communication system;

[0116] FIG. 2 shows a schematic representation of an apparatus for the 5G communication system of FIG. 1;

[0117] FIG. 3 shows a schematic representation of a communication device;

[0118] FIG. 4 shows an example signalling and operations diagram between user equipments and network nodes for determining a list of neighbour group identities;

[0119] FIG. 5 shows an example signalling and operations diagram between a user equipment and network nodes for determining a list of neighbour group identities;

[0120] FIG. 6 shows another example signalling and operations diagram between user equipments and network nodes for determining a list of neighbour group identities;

[0121] FIG. 7 shows another example signalling and operations diagram between a user equipment and network nodes for determining a list of neighbour group identities;

[0122] FIG. 8 shows an example method flow diagram performed by an apparatus;

[0123] FIG. 9 shows another example method flow diagram performed by an apparatus; and

[0124] FIG. 10 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the method of FIGS. 8 to 9.Detailed Description

[0125] The following describes signalling and operations that may be performed in relation closed subscriber groups (CSGs) and closed access groups (CAGs) in 4G and 5G communication systems, and beyond.

[0126] In particular, the following considers the determining and transmitting of identities of CSGs (e.g., CSG IDs) or identities of CAGs (e.g., CAG IDs) between entities of communication system. The following considers potential issues regarding the amount of data that is transmitted related to the CSG IDs / CAG IDs, and how this may be reduced.

[0127] 4G defines a closed subscriber group (CSG) method to be used by femtos. A CSG is a set of users with connectivity access to a femtocell provided by a femto. Each CSG is identified by a corresponding identity (ID) (or identifier) for the CSG (e.g., CSG-ID). A CSG ID is a unique identifier within the scope of a public land mobile network (PLMN), which identifies a CSG in the PLMN associated with a CSG cell, or group of CSG cells. The CSG thus identifies a set of subscribers (e.g., group of subscribers) that are permitted, or otherwise authorised, to access one or more femtocells of a PLMN that corresponds to the CSG ID(s) of the set of subscribers. Stated differently, a set of subscribers and a femtocell of a PLMN that the set of subscribers are permitted, or otherwise authorised, to access are associated with a same CSG ID. A CSG ID may be a 27 bitstring (i.e., a bitstring having a length of 27 bits). A RAN node (e.g., base station) hosting CSG cells may be called a home eNodeB (HeNB), 4G / LTE femto base station, or a 4G femto.

[0128] A femto cell refers to a cell (e.g., a region of coverage) provided by a femto. A femto may be considered as being a small form factor, low-power cellular base station that provides a femtocell with a region of coverage corresponding to low-power. A femto is typically designed for use in a home or small business. The use of femtocells allows network coverage in places where the signal to larger cells (e.g., cells having a greater coverage area than femtocells, cell’s having greater power than a femto) might be too weak. Furthermore, the provision of femtocells lower contention on those larger cells by forming a connection from the end user, through an internet connection, to the operator's private network infrastructure located elsewhere.

[0129] The femto, or femtocell, maintains a list of CSG identifiers that are allowed to access specific services via the femtocell. This list is labelled as an access control list in 4G. Stated differently, the access control list is a list of CSG identifiers that are authorized to access the network service. A network operator creates and manages the access control list. The access control list is stored in the network's database and is updated by the network operator as needed. The access control list can be configured to allow or deny access to specific network services for each CSG ID.

[0130] In order to access services via a CSG femtocell, a communication device having a subscription to a specific CSG is configured with the CSG ID corresponding to that CSG. CSGmembership of a communication device is configured in the user subscription data and on the communication device. Subsequently, when a femtocell is configured in CSG mode, the femtocell transmits those CSG identifiers corresponding to CSGs served by the femtocell (e.g., the femtocell’s access control list). The communication device receives the CSG identifiers that are transmitted (e.g., in a list of CSG identifiers that is transmitted), and compares the CSG identifiers that are received to CSG identifier(s) configured at the communication device. Communication devices configured with at least one CSG identifier that is included in the femtocell's access control list are allowed to use the femtocell resources / connect to the femtocell. When a communication device tries to connect to a CSG cell (e.g., when the communication device believes itself to be configured with a CSG identifier corresponding to a CSG identifiers transmitted by the femtocell), the network (e.g., a mobility management entity (MME)) determines whether the communication device is allowed to do so, based on the subscription data for that communication device. The concept of CSG cells and handover between CSG cells in E-UTRAN and between UTRAN and E-UTRAN is described in 3GPP TS 23.401 clause 5.5, and TS 36.300 clause 10.5.

[0131] Several network operators have currently deployed 4G femtos in several countries and have also deployed 5G. Therefore, mobility from 5G to 4G femtos using CSG cells is to be considered. 3GPP envisions the introduction of 5GHome gNB (HgNB), also called 5G femtos, in Rel. 19. In one mode of HgNB cells, called closed access mode, certain subscribers are allowed to access the HgNB cell, similar to HeNBs. To enable this (closed access) mode of operation for an HgNB cell, 3GPP envisions the re-use of the CAG concept which was introduced in 5G in 3GPP Rel. 16 for non-public networks (NPNs).

[0132] 5G defines a CAG method for access nodes of non-public networks (NPNs). A CAG is a set of subscribers (or users) with connectivity access to a femtocell. Each CAG is identified by a corresponding identity (or identifier) for the CAG (e.g., CAG-ID). The CAG ID thus identifies a group of subscribers that are permitted, or otherwise authorised, to access one or more access nodes of a NPN that corresponds to the CAG identified s) configured at the NPN. Stated differently, a set of subscribers and an access node of a NPN that the set of subscribers are permitted, or otherwise authorised, to access are associated with a same CAG identifier. A CAG identifier may be a 32 bitstring (i.e., a bitstring having a length of 32 bits).

[0133] A cell may be provided by an NPN (also referred to as an NPN cell herein) which maintains a list of CAG identifiers that are allowed to access specific services via the NPN cell. The list of CAG identifiers comprises one or more IDs of CAGs that are authorized to access the network service. The network operator creates and manages this access control list of CAGIDs. The access control list of CAG IDs is stored in the network's database and is updated by the network operator as needed. The access control list of CAG IDs can be configured to allow or deny access to specific network services for each CAG ID on the access control list of CAG IDs.

[0134] In order to access services, via an NPN cell of a CAG, a communication device having a subscription to a specific CAG is configured with the CAG ID corresponding to that CAG. CAG membership of a communication device (e.g., that the communication device has a subscription to a specific CAG) is configured in the user subscription data and on the communication device. Subsequently, when an NPN cell is configured in CAG mode (e.g., a mode in which access to connectivity services provided by the NPN cell is controlled according to membership in a CAG), the NPN cell transmits those CAG identifiers corresponding to CAGs served by the NPN cell configured in CAG mode. The communication device receives the CAG identifiers ((e.g., a list of CAG identifiers), and compares the CAG identifiers that are transmitted by the NPN cell and received by the communication device to the CAG identified s) configured at the terminal. Communication devices configured with at least one CAG identifier that is included in the NPN cell's list of CAG identifiers are allowed to use the NPN cell’s resources. When a communication device tries to connect to a NPN cell of a CAG (e.g., when the communication device believes itself to be configured with a CAG identifier corresponding to a transmitted CAG identifier), the network (e.g., an access and mobility function) checks whether the communication device is allowed to do so, based on the subscription data for that communication device.

[0135] CAG methods were originally introduced in the context of public network integrated non-public networks (PNI-NPNs) for preventing communication device(s) that are not allowed to access an NPN via the associated cell(s) from automatically selecting and accessing the associated cell(s) configured in CAG mode. C AG-based access control was introduced in 3 GPP Release-16. The existing 5G concept of PNI-NPN and of CAG cells is described in 3GPP TS 23.501 clause 5.30.3.1, and TS 38.300 clause 16.7.

[0136] With femtos being introduced in 5G communication networks, a femtocell provided by a 5G femto may be configured for a CAG mode.

[0137] When introducing the concept of 5G femto in 3GPP Rel. 19, mobility from HgNB cells (e.g., using CAG cells) to HeNBs (e.g., using CSG cells) and vice-versa should be considered. For example, an enterprise may introduce 5G femto on top of existing LTE femto deployment.

[0138] For intersystem mobility (e.g., from 5G to 4G), an AMF may send CSG IDs that are permitted / allowed for a UE. However, in this case, the AMF sends a ‘full’ list of allowed CSGIDs that are applicable in the whole of the public land mobile network (PLMN). Sending the full list of CSG IDs that are applicable PLMN wide means that the list is potentially large in size and so the signalling overhead will also be large (wherein overhead considerations are critical over the radio interface when sent to the UE). Furthermore, many of the CSG IDs of the full list are not useful for the UE in its current location (e.g., when the UE is not going to have idle mobility or handover to a CSG cell). The sending of CSG IDs not relevant to the UE in its current location creates unnecessary signalling overhead. Furthermore, by sending the full list of allowed CSG IDs applicable PLMN wide, the frequency of transmissions of the full list from the AMF to the UE will be high due to the fact that any update of a CSG ID in the list would trigger the AMF to send the full (updated) list again. The transmission of the full (updated) list would occur even if the CSG ID update concerns a remote cell that is far away from the UE. Updates of the CSD IDs in the list may be frequent (e.g. a femto owner updating an allowed subscriber list). Therefore, this creates an unnecessary signalling overhead.

[0139] For intrasystem mobility (e.g., 5G to 5G), in the example of a 5G system, an AMF may send, to a UE, a ‘full’ list of CAG IDs that are permitted / allowed for the UE. Sending the full list of CAG IDs that are applicable PLMN wide means that the list is potentially large in size and so the signalling overhead will also be large (wherein overhead considerations are critical over the radio interface when sent to the UE).

[0140] An NG-RAN node may send, to an AMF, a list of CAG IDs that the NG-RAN supports (in a tracking area (TAI) of the NG-RAN), and a list of TAs that neighbour the TAI of the NG-RAN (e.g., TA2). This allows an AMF to approximate a list of CAG IDs that neighbour TAI based on the information received from the NG-RAN. This approximation may be used to reduce the size of a list of CAG IDs to be provided to a UE. However, this is suboptimal because a CAG cell of TA2 is not necessarily a radio neighbour of a cell of TAI. As TA2 is simply a neighbour of TAI, this simply means that there is at least one cell of TA2 that is neighbouring at least one cell of TAI. Accordingly, the reduced list approximated in this manner and provided to a UE may not be optimal, and unnecessary information (i.e., unnecessary CAG IDs) is provided to the UE. Therefore, use of such a reduced list creates an unnecessary signalling overhead.

[0141] An example to illustrate the process described above is as follows:- gNBl supports TAI (cells 1,2, 3, ...,10). Cell 1 supports CAG 1, cell2 supports CAG 2, cell 3 supports CAG 3. Cells 4 to 10 are not CAG cells.- gNB2 supports TA2 (cells 11, .., 20). Cell 11 supports CAG 11, cell 12 supports CAG 12, cell 13 supports CAG 13. Cells 14 to 20 are not CAG cells.- Cell 11 is neighbour of cell 1. Therefore TA2 is a neighbour of TAI.- Cells 12, 13 are NOT neighbouring any cell of TAI. gNBl sends to AMF1: TAI supports CAG IDs =(CAG 1, 2, 3) + TA2 is neighbour of TAI gNB2 sends to AMF1: TA2 supports CAG IDs = (CAG 11,12,13)Upon receipt from gNBl and gNB2, AMF1 builds database for TAI and approximates that neighbour CAG IDs for TAI are CAG 11,12, and 13.

[0142] However, in this example, cells 12, 13 are not neighbouring any of the cells of TAI. Therefore, the approximation is inaccurate, and this leads to unnecessary signalling overhead to the UE.

[0143] One or more of the following examples aim to address one or more of the problems identified above.

[0144] In examples, there is a method performed by a RAN, node (e.g., NG-RAN) comprises: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node. The method also comprises providing, to a core network node (e.g., AMF), information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0145] In some examples, the at least one neighbour group identity is one of: an identity for a closed subscriber group (e.g., CSG ID), or an identity for a closed access group (e.g., CAG ID).

[0146] In some examples, the method comprises: receiving, from a UE in a first cell of the TA, a message comprising the at least one neighbour group identity that is associated with a second cell that neighbours the first cell of the TA, and including, in the data record, the at least one neighbour group identity based on the TA.

[0147] In some examples, the method comprises: receiving, from an operations and maintenance (O&M) entity, data related to the data record, wherein the data comprises the at least one neighbour group identity, and determining the data record based on the data that has been received.

[0148] One or more of the examples described herein lead to a reduction in the size / length of a list of allowed CAG IDs / CSG IDs being transmitted to a UE, which reduces signalling overhead. The CAG / CSG IDs transmitted to the UE are those that are relevant to the UE (i.e., the minimum number of CAG / CSG IDs are provided. Reducing the size / length of the list ofallowed CAG IDs / CSG IDs also means that the transmitting of the list by the AMF is less frequent. This is because fewer IDs in the list will statistically mean that there will be fewer updates compared to a list with more IDs.

[0149] In examples, there is a method performed by a core network node (e.g., AMF) comprising: receiving, from a RAN node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a TA supported by the RAN node. The method also comprising: storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0150] In some examples, the method also comprises: receiving, from a UE, a registration request message, and in response to the registration request message, determining a registration area, RA, for the user equipment. The method further comprising: identifying, using the data that has been stored, for each TA of the RA, at least one group identity which is either: a home group identity of the TA, or a neighbour group identity of the TA, filtering a list of group identities that are permitted to be accessed by the user equipment based on the identifying, so to obtain a filtered list of group identities, and providing, to the UE, the filtered list of group identities.

[0151] These examples will be described in more detail below, alongside FIGS. 4 to 7.

[0152] Before explaining the examples above in greater detail, an example communication device (e.g., UE) (as shown in FIG. 3) that is capable of providing information related to neighbour CSG / CAG IDs to a network will be described. The communication device is part of a communication system (as shown in FIG. 1). The UE is able to communicate with one or more of the entities of the communication system, such as an NG-RAN (as shown in FIG. 1) via an apparatus (as shown in FIG. 2), which may be part of / comprised in a base station.

[0153] Certain general aspects of the communication system and the communication device are briefly explained with reference to FIGS. 1 to 3 to assist in understanding the technology underlying the described examples.

[0154] FIG. 1 shows a schematic representation of a 5G communication system 100. The wireless communication system 100 comprises one more communication devices 102 such as user equipments (UEs), or terminals. The wireless communication system 100 comprises a 5G system (5GS). The 5GS comprises a 5G radio access network (5G-RAN) 106, a 5G core network (5GC) 104 comprising one or more network functions (NF), one or more application functions (AFs) 108, and one or more data networks (DNs) 110.

[0155] The 5G-RAN 106 may comprise one or more gNodeB (gNB) distributed unit (DU) functions connected to one or more gNodeB (gNB) centralized unit (CU) functions.

[0156] The 5GC 104 comprises an access and mobility management function (AMF) 112, a session management function (SMF) 114, an authentication server function (AUSF) 116, a user data management (UDM) 118, a user plane function (UPF) 120, a network exposure function (NEF) 122 and / or other NFs. Some of the examples as shown below may be applicable to 3GPP 5G standards. However, some examples may also be applicable to 5G-advanced, 4G, 3G and other 3 GPP standards.

[0157] In a wireless communication system 100, such as that shown in FIG. 1, communication devices 102, such as for example, terminals, user apparatuses, user equipments (UE), and / or machine-type communication devices are provided with wireless access via at least one base station or similar wireless transmitting and / or receiving node or point. The communication device 102 is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices. The communication device 102 may access a carrier provided by a base station or access point, and transmit and / or receive communications on the carrier.

[0158] FIG. 2 illustrates an example of an apparatus 200. The apparatus 200 may be for the 5G communication system of FIG. 1. The apparatus 200 may be for controlling a function of one or more network entities and / or network functions, such as the entities of the 5G-RAN or the 5GC as illustrated on FIG. 1. The apparatus 200 comprises at least one random access memory (RAM) 211a, at least one read only memory (ROM) 211b, at least one processor 212, 213 and an input / output interface 214. The at least one processor 212, 213 is coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects or examples. The software code 215 may be stored in the ROM 211b. The apparatus 200 may be interconnected with another apparatus 200 controlling another entity / function of the 5G-AN or the 5GC. In some examples, apparatus 200 may be configured to provide one or more functions of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to perform at least some functionality of a particular function of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to operate as a particular function of the 5G-AN or the 5GC. In alternative examples, apparatus 200 may be configured to perform at least some functionality of two or more functions of the 5G-AN and / or the 5GC. For example, apparatus 200 may be configured to operate as two ormore functions of the 5G-AN and / or the 5GC. The apparatus 200 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples.

[0159] FIG. 3 illustrates an example of a communication device 300. The communication device 300 may be similar to the communication device 102 illustrated in FIG. 1. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples of a communication device 300 are a user equipment, a terminal, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CIoT) device, or a terrestrial / maritime / aerial vehicle such as a car, a truck, a boat, an air plane, or a drone, or any combinations of these or the like. The communication device 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

[0160] The communication device 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In FIG. 3, a transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

[0161] The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a. The communication device 300 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples.

[0162] The processor, storage and other relevant control apparatus may be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 304. Thecommunication device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

[0163] FIG. 4 shows an example signalling and operations diagram between user equipments and network nodes for determining a list of neighbour group identities.

[0164] In FIG. 4, the communications occur between a first UE (UE1), a second UE (UE2), a third UE (UE3), a further UE (UEx), a RAN node (e.g., NG-RAN node) and a core network node (e.g., AMF).

[0165] At S401, the RAN node receives, from a UE (e.g., one of UE1, UE2, or UE3), a CSG ID (herein referred to as ‘the neighbour CSG ID’). The neighbour CSG ID is a CSG ID that is supported in a cell that neighbours at least one cell of a TA supported by the RAN node. For example, the RAN node may support (at least) the TA (e.g., ‘TAI’).

[0166] The (neighbour) CSG ID is an example of a group identity.

[0167] The neighbour CSG ID may be received in a measurement report from the UE. The RAN node may provide signalling to the UE to trigger a measurement report, wherein the measurement report comprising the neighbour CSG ID is received in response to the signalling. The trigger may be associated with an automatic neighbour relations (ANR) process.

[0168] ANR enables the generation of automatic neighbour relations between base station cells and neighbouring base stations cells. ANR neighbour relation helps in supporting mobility, load balancing and dual connectivity. An ANR function manages the conceptual Neighbour Relation Table (NRT). An ANR neighbour detection function finds new neighbours and adds them to the NRT. An ANR neighbour removal function removes outdated neighbour from the NRT.

[0169] In some examples, the RAN node receives, from multiple UEs (e.g., from UE1, UE2, UE3) served by a cell of the RAN node, measurement reports that each include at least one CSG ID measured from a 4G CSG cell that neighbours a cell of the TA supported by the RAN node.

[0170] For example, the RAN node receives, from a UE in a first cell of the TA, a message comprising at least one neighbour CSG ID that is associated with a second cell that neighbours the first cell of the TA. Alternatively, or additionally, the RAN node receives, from a UE in a third cell of a further TA that is supported by the RAN node, a further message comprising a further CSG ID associated with a fourth cell that neighbours the third cell of the further TA.

[0171] At S402, the RAN node determines a data record for CSG IDs. The data record is associated with the RAN node. The determining of the data record may comprise: generating(or creating) the data record, for CSG IDs to then be stored in the data record. The determining of the data record may comprise: updating the data record, wherein CSG IDs are added / removed / updated in the data record.

[0172] The RAN node stores (or includes) the neighbour CSG ID in the data record. The RAN node may store the neighbour CSG ID in the data record per TA supported by the RAN node. Stated differently, the RAN node includes, in the data record, the neighbour CSG ID based on the TA. For example, each data entry (for a CSG ID) in the data record may have an associated TA. The TA associated with the CSG ID may be used as an index to store the CSG ID in the data record. For example, if neighbour CSG ID3 was a neighbour of cell 1 of TAI that is supported by the RAN node, then the neighbour CSG ID3 is stored in the data record and associated with TAI in the data record.

[0173] In some examples, the RAN node includes the neighbour CSG ID(s) that have been received (in one or more measurement reports) from the UE (or the UEs) in the data record.

[0174] In some examples, the RAN node determines a list of neighbour CSG IDs, per TA, by cumulating the list of neighbour CSG IDs of all cells of the TA based on the CSG ID(s) received from the UE (or UEs).

[0175] In this context, the data record is a store of data. In other examples, a database, a data store, a file, or a record, may be used instead of the data record. These terms may be used interchangeably in this context.

[0176] At S403, the RAN node provides, to the AMF, information related to the data record. In some examples, the information related to the data record comprises the neighbour CSG ID. In some examples, the information related to the data record comprises a list of neighbour CSG IDs per TA (from the data record). A list of neighbour CSG IDs comprises one or more neighbour CSG IDs.

[0177] In some examples, the RAN node provides the data record (or the contents of the data record), to the AMF. For example, the RAN node provides at least one data entry from the data record to the AMF.

[0178] In some examples, the RAN node sends the information to AMF in a next generation application protocol (NGAP) message. For example, the NGAP message may be a RAN configuration update message, or an NG setup request message.

[0179] In some examples, the RAN node also provides the information related to the data record to O&M (not shown in FIG. 4). This may be in addition to the providing of the information to the AMF.

[0180] An example of an NGAP message comprising the information related to the data record is shown in Table 1 below. In Table 1, the information is included in a parameter comprising neighbour CSG IDs arranged in a list, per TA. The form / format of the information being included in a list is an example only. The information may be provided in any suitable format.Table 1 : Example of parameters included in an NGAP RAN configuration update message, wherein the message has been extended to include a ‘Neighbour CSG Information List per TA’ (based on 3GPP TS 38.413 clause 9.2.6 4 RAN CONFIGURATION UPDATE).

[0181] For example, the RAN node may provide:Neighbour CSG Information List per TA = TAI [neighbour CSG ID 1, neighbour CSG ID 3, neighbour CSG ID4]Neighbour CSG Information List per TA = TA2 [neighbour CSG ID2, neighbour CSG ID5, neighbour CSG ID6]

[0182] It should be understood that the values included above are provided as an example only, to aid in the understanding of the disclosure.

[0183] At S404, the AMF stores data associated with the TAI, wherein the data comprises: for the TAI, the neighbour CSG ID. The storing of the data is based on the information received from the RAN node (in S403). In some examples, a plurality of CSG IDs associated with TAI are stored.

[0184] In some examples, the AMF stores data for a plurality of different TAs.

[0185] In some examples, the AMF stores, for TAI, a list of neighbour CSG IDs received from the RAN node.

[0186] At S405, the further UE (UEx) triggers a registration procedure. UEx provides, to the AMF, a register request message. In some examples, UEx sends a non-access stratum (NAS) register request message to AMF. UEx may trigger the registration procedure in response to moving to a ‘new’ registration area (RA).

[0187] At S406, the AMF determines an RA for UEx (e.g., in response to or based on receiving the register request message of S405). The determined RA comprises at least one TA. For example, the RA for UEx comprises at least TAI .

[0188] The AMF then filters a first list of CSG IDs based on: the data, and the at least one TA included in the RA of UEx. Each CSG ID in the first list identifies a CSG that UEx is permitted to access.

[0189] In some examples, the AMF removes at least one CSG ID from the first list based on: the data, and the at least one TA included in the RA of UEx.

[0190] Before filtering, the first list of CSG IDs is obtained by the AMF. In some examples, the AMF receives the first list of CSG IDs from a network node. In some examples, the AMF receives the first list of CSG IDs from an operation and maintenance entity. The first list of CSG IDs comprises CSG IDs of CSGs that UEx is permitted (or allowed) to access across the PLMN.

[0191] For example, the AMF determines the RA for UEx to be: RA = (TAI, TA2).

[0192] The AMF identifies, using the data that has been stored, for each TA (e.g., TAI, TA2) of the RA, at least one neighbour CSG ID of TA1 / TA2. The AMF then filters the first list of CSG IDs based on the identifying of the at least one CSG ID, so to obtain a filtered list of group identities. The filtering of the first list may comprise removing CSG IDs from the first list that were not identified as neighbour CSG ID.

[0193] Stated differently, the AMF filters the first list of CSG IDs (the first list being a PLMN- wide list of CSG IDs) permitted for the UEx based on the data stored in S404. The AMF reduces the size of the first list of CSG IDs (before sending to UEx) by removing, from the full list of CSG IDs, those CSG IDs that were not identified as neighbour CSG ID for the RA of UEx.

[0194] The filtered list of CSG IDs is associated with UEx.

[0195] At S407a, the AMF provides, to UEx, the filtered list of CSG IDs. In some examples, the AMF sends an NAS (Non Access Stratum) register accept message to UEx including the filtered list of CSG IDs. In some examples, the AMF sends an NAS UE configuration update command to UEx including the filtered list of CSG IDs.1

[0196] At S407b, the AMF provides, to the RAN node, the filtered list of CSG IDs. In some examples, the AMF sends an NGAP message to the RAN node including the filtered list of CSG IDs. The filtered list of CSG IDs may be comprised within a mobility restriction list information element (IE).

[0197] The RAN node stores the received filtered list of CSG IDs for UEx.

[0198] In some examples, S407a and S407b may be combined. For example, an NAS register accept of S407a may be combined with the NGAP message of S407b.

[0199] At S408, the UEx stores the filtered list of CSG IDs. For example, the UEx may store the filtered list in non-volatile memory associated with UEx (e.g., in non-volatile memory of a universal subscriber identity module (USIM) of UEx).

[0200] An example to illustrate the process of FIG. 4 is as follows:- 5G gNB (RANI) supports TAI (cells 1,2, 3, ...,10). Cell 1 supports CAG 1, cell2 supports CAG2, cell 3 supports CAG 3. Cells 4 to 10 are not CAG cells.- 4G eNB (RAN2) supports TA2 (cells 11, .., 20). Cell 11 supports CSG 11, cell 12 supports CSG 12, cell 13 supports CSG 13. Cells 14 to 20 are not CSG cells.- Cell 11 is neighbour of cell 1. Therefore TA2 is a neighbour of TAI.- Cells 12, 13 are not neighbouring any cell of TAI.RANI sends to AMF1 : TAI supports CAG IDs = (CAG 1,2,3) + list of neighbour CSG IDs (that neighbour a cell of TAI) = CSG 11. (N.B. CSG 12, 13 are not measured by any UEs under the cells of TAI because cells 12, 13 are not neighbouring any cell of TAI)AMF1 stores the information received from RANI, per TA.

[0201] When the AMF1 is to provide permitted CSG IDs to a UE (e.g., in response to a register accept message from the UE), the AMF1 knows the CSG IDs that are relevant to an RA of the UE (i.e., CSG IDs that are neighbouring a cell of a TA in the RA). In this manner, the list of CSG IDs provided to the UE has a reduced size (or minimum size) relative to a PLMN-wide list of CSG IDs. Signalling overhead is therefore reduced.

[0202] It should be understood that the values provided above in the example are given as examples only to aid in the understanding of the disclosure.

[0203] Similarly, for a 5G-5G case, when an AMF is to provide permitted CAG IDs to a UE (e.g., in response to a register accept message from the UE), the AMF knows the CAG IDs that are relevant to an RA of the UE (i.e., CAG IDs supported in a TA in the RA, and CAG IDs that are neighbouring a cell of a TA in the RA). In this manner, the list of CAG IDs provided to the UE has a reduced size (or minimum size) relative to a PLMN-wide list of CSG IDs. Signallingoverhead is therefore reduced. A similar 5G-5G case will be described in more detail alongside FIGS. 6 and 7.

[0204] It should be understood that the values provided above in the example are given as examples only to aid in the understanding of the disclosure.

[0205] FIG. 5 shows another example signalling and operations diagram a between a user equipment and network nodes for determining a list of neighbour group identities.

[0206] In FIG. 5, the communications occur between an O&M entity, a further UE (UEx), a RAN node (e.g., NG-RAN node) and a core network node (e.g., AMF).

[0207] At S501, the O&M entity provides, to the RAN node, data (or information) related to a neighbour CSG ID. The neighbour CSG ID is a CSG ID that is supported by a cell that neighbours at least one cell of a TA (e.g., TAI) supported by the RAN node.

[0208] The (neighbour) CSG ID is an example of a group identity.

[0209] In some examples, the O&M provides the data comprising the at least one neighbour CSG ID.

[0210] In some examples, the O&M provides the data comprising a plurality of neighbour CSG IDs. In some examples, the O&M provides the plurality of neighbour CSG IDs to the RAN node.

[0211] In some examples, the O&M entity configures the RAN node with the at least one neighbour CSG ID. In some examples, the O&M entity configures the RAN node with a data record comprising the at least one neighbour CSG ID.

[0212] At S502, the RAN node determines a data record for CSG IDs. The data record is associated with the RAN node. The RAN node determines the data record based on the data from the O&M entity. The determining of the data record may comprise: storing, in the data record associated with the RAN node, the at least one neighbour CSG ID based on the data from the O&M.

[0213] The RAN node stores the neighbour CSG ID in the data record. The RAN node may store the neighbour CSG ID in the data record per TA supported by the RAN node. Stated differently, the RAN node includes, in the data record, the neighbour CSG ID based on the TA. For example, each data entry (for a CSG ID) in the data record may have an associated TA. The TA associated with the CSG ID may be used as an index to store the CSG ID in the data record.

[0214] In some examples, the RAN node is configured with the data record comprising, for each supported TA, a list of neighbour CSG ID(s).

[0215] In some examples, the RAN node is configured, for each of its cells, with a list of neighbour CSG ID(s). The RAN node then determines the lists for all cells of each TA to determine the data record comprising, for each supported TA, the list of neighbour CSG ID(s).

[0216] In this context, the data record is a store of data. In other examples, a database, a data store, a file, or a record, may be used instead of the data record. These terms may be used interchangeably in this context.

[0217] At S503, the RAN node provides, to the AMF, information related to the data record. In some examples, the information related to the data record comprises the neighbour CSG ID. In some examples, the information related to the data record comprises a list of neighbour CSG IDs per TA (from the data record).

[0218] In some examples, the RAN node provides the data record (or the contents of the data record), to the AMF. For example, the RAN node provides at least one data entry from the data record to the AMF.

[0219] In some examples, the RAN node sends the information to AMF in a next generation application protocol (NGAP) message. For example, the NGAP message may be a RAN configuration update, or an NG setup request message.

[0220] An example of an NGAP message comprising the information related to the data record is shown in Table 2 below. In Table 2, the information is included in a parameter comprising neighbour CSG IDs arranged in a list, per TA. The form / format of the information being included in a list is an example only. The information may be provided in any suitable format.Table 2: Example of parameters included in an NGAP RAN configuration update message, wherein the message has been extended to include a ‘Neighbour CSG Information List per TA’ (based on 3GPP TS 38.413 clause 9.2.6 4 RAN CONFIGURATION UPDATE).

[0221] For example, the RAN node may provide:Neighbour CSG Information List per TA = TAI [neighbour CSG ID1, neighbour CSG ID 3, neighbour CSG ID4]Neighbour CSG Information List per TA = TA2 [neighbour CSG ID2, neighbour CSG ID 5, neighbour CSG ID6]

[0222] It should be understood that this is provided as an example only, to aid in the understanding of the disclosure.

[0223] At S504, the AMF stores data associated with the TAI, wherein the data comprises: for the TAI, the neighbour CSG ID. The storing of the data is based on the information received from the RAN node (in S503). In some examples, a plurality of CSG IDs associated with TAI are stored.

[0224] In some examples, the AMF stores data for a plurality of different TAs.

[0225] In some examples, the AMF stores, for TAI, a list of neighbour CSG IDs received from the RAN node.

[0226] At S505, the further UE (UEx) triggers a registration procedure. UEx provides, to the AMF, a register request message. In some examples, UEx sends a non-access stratum (NAS) register request message to AMF. UEx may trigger the registration procedure in response to moving to a ‘new’ registration area (RA).

[0227] At S506, the AMF determines an RA for UEx (e.g., in response to receiving the register request message of S505). The determined RA comprises at least one TA. For example, the RA for UEx comprises at least TAI .

[0228] The AMF then filters a first list of CSG IDs based on: the data, and the at least one TA included in the RA of UEx. Each CSG ID in the first list identifies a CSG that UEx is permitted to access.

[0229] Before filtering, the first list of CSG IDs is obtained by the AMF. In some examples, the AMF receives the first list of CSG IDs from a network node. In some examples, the AMF receives the first list of CSG IDs from an operation and maintenance entity. The first list of CSG IDs comprises CSG IDs of CSGs that UEx is permitted (or allowed) to access across the PLMN.

[0230] For example, the AMF determines the RA for UEx to be: RA = (TAI, TA2).

[0231] The AMF identifies, using the data that has been stored, for each TA (e.g., TAI, TA2) of the RA, at least one CSG ID that is a neighbour CSG ID of TA1 / TA2. The AMF then filters the first list of CSG IDs based on the identifying of the at least one CSG ID, so to obtain a filtered list of group identities. The filtering of the first list may comprise removing CSG IDs from the first list that were not identified as a neighbour CSG ID.

[0232] Stated differently, the AMF filters the first list of CSG IDs (that is PLMN wide) permitted for the UEx based on the data stored in S504. The AMF reduces the size of the first list of CSG IDs (before sending to UEx) by removing, from the full list of CSG IDs, those CSG IDs that were not identified as a neighbour CSG ID for the RA of UEx.

[0233] The filtered list of CSG IDs is associated with UEx.

[0234] At S507a, the AMF provides, to UEx, the filtered list of CSG IDs. In some examples, the AMF sends an NAS register accept message to UEx including the filtered list of CSG IDs. In some examples, the AMF sends a NAS UE configuration update command to UEx including the filtered list of CSG IDs.

[0235] At S507b, the AMF provides, to the RAN node, the filtered list of CSG IDs. In some examples, the AMF sends an NGAP message to the RAN node including the filtered list of CSG IDs. The filtered list of CSG IDs may be comprised within a mobility restriction list information element (IE).

[0236] The RAN node stores the received filtered list of CSG IDs for UEx.

[0237] In some examples, S507a and S507b may be combined. For example, an NAS register accept of S507a may be combined with the NGAP message of S507b.

[0238] At S508, the UEx stores the filtered list of CSG IDs. For example, the UEx may store the filtered list in non-volatile memory associated with UEx (e.g., in non-volatile memory of a universal subscriber identity module (USIM) of UEx).

[0239] FIG. 6 shows another example signalling and operations diagram between user equipments and network nodes for determining a list of neighbour group identities.

[0240] In FIG. 6, the communications occur between a first UE (UE1), a second UE (UE2), a third UE (UE3), a further UE (UEx), a RAN node (e.g., NG-RAN node) and a core network node (e.g., AMF).

[0241] At S601, the RAN node receives, from a UE (e.g., one of UE1, UE2, or UE3), a CAG ID (herein referred to as ‘the neighbour CAG ID’). The neighbour CAG ID a CSG ID that is supported in a cell that neighbours at least one cell of a TA supported by the RAN node. For example, the RAN node may support (at least) the TA (e.g., ‘TAI’).

[0242] The (neighbour) CAG ID is an example of a group identity.

[0243] The neighbour CAG ID may be received in a measurement report from the UE. The RAN node may provide signalling to the UE to trigger a measurement report, wherein the measurement report comprising the neighbour CAG ID is received in response to the signalling. The trigger may be associated with an ANR process.

[0244] In some examples, the RAN node receives, from multiple UEs (e.g., from UE1, UE2, UE3) served by a cell of the RAN node, measurement reports that each include at least one CAG ID measured from a 5G CAG cell that neighbours a cell of a TA (e.g., TAI) supported by the RAN node.

[0245] For example, the RAN node receives, from a UE in a first cell of the TA, a message comprising at least one neighbour CAG ID that is associated with a second cell that neighbours the first cell of the TA. Alternatively, or additionally, the RAN node receives, from a UE in a third cell of a further TA that is supported by the RAN node, a further message comprising a further CAG ID associated with a fourth cell that neighbours the third cell of the further TA.

[0246] At S602, the RAN node determines a data record for CAG IDs. The data record is associated with the RAN node. The determining of the data record may comprise: generating (or creating) the data record, for CAG IDs to then be stored in the data record. The determining of the data record may comprise: updating the data record, wherein CAG IDs are added / removed / updated in the data record.

[0247] The RAN node stores (or includes) the neighbour CAG ID (received from the UE) in the data record. The RAN node may store the neighbour CAG ID in the data record per TA supported by the RAN node. Stated differently, the RAN node includes, in the data record, the neighbour CAG ID based on the supported TA associated with the neighbour CAG ID. For example, each data entry (for a CAG ID) in the data record may have an associated TA. The TA associated with the CAG ID may be used as an index to store the CAG ID in the data record. For example, if neighbour CAG ID3 was a neighbour of cell 1 of TAI that is supported by the RAN node, then the neighbour CAG ID3 is stored in the data record and associated with TAI in the data record.

[0248] In some examples, the data record comprises: for a TA that is supported by the RAN node (e.g., TAI), at least one CAG ID that is supported in TAI (e.g., at least one ‘home’ CAG ID).

[0249] In some examples, the RAN node includes the neighbour CAG ID(s) that has been received (in one or more measurement reports) from the UE (or the UEs) in the data record.

[0250] In some examples, the RAN node determines a list of neighbour CAG IDs, per TA, by cumulating the list of neighbour CAG IDs of all cells of the TA based on the CAG ID(s) received from the UE (or UEs).

[0251] In this context, the data record is a store of data. In other examples, a database, a data store, a file, or a record, may be used instead of the data record. These terms may be used interchangeably in this context.

[0252] At S603, the RAN node provides, to the AMF, information related to the data record. In some examples, the information related to the data record comprises the neighbour CAG ID. In some examples, the information related to the data record comprises a list of neighbour CAG IDs per TA (from the data record).

[0253] In some examples, the information related to the data record may comprise the at least one CAG ID that is supported in TAI (e.g., the at least one home CAG ID).

[0254] In some examples, the RAN node provides the data record (or the data of the data record), to the AMF. For example, the RAN node provides at least one data entry from the data record to the AMF.

[0255] In some examples, the RAN node sends the information to the AMF in an NGAP message. For example, the NGAP message may be a RAN configuration update message, or an NG setup request message.

[0256] In some examples, the RAN node also provides the information related to the data record to an O&M entity (not shown in FIG. 6). This may be in addition to the providing of the information to the AMF.

[0257] An example of an NGAP message comprising the information related to the data record is shown in Table 3 below. In Table 3, the information is included in a parameter comprising neighbour CAG IDs arranged in a list, per TA. The form / format of the information being included in a list is an example only. The information may be provided in any suitable format.Table 3: Example of parameters included in an NGAP RAN configuration update message, wherein the message has been extended to include a ‘Neighbour CAG Information List per TA’ (based on 3GPP TS 38.413 clause 9.2.6 4 RAN CONFIGURATION UPDATE).

[0258] For example, the RAN node may provide:Neighbour CAG Information List per TA = TAI [neighbour CAG ID 1, neighbour CAG ID 3, neighbour CAG ID 4]Neighbour CAG Information List per TA = TA2 [neighbour CAG ID 2, neighbour CAG ID5, neighbour CAG ID6]

[0259] It should be understood that this is provided as an example only, to aid in the understanding of the disclosure.

[0260] At S604, the AMF stores data associated with the TAI, wherein the data comprises: for the TAI, the neighbour CAG ID. The storing of the data is based on the information received from the RAN node (in S603). In some examples, a plurality of CAG IDs associated with TAI are stored.

[0261] In some examples, the AMF stores data for a plurality of different TAs.

[0262] In some examples, the AMF stores, for TAI, a list of neighbour CAG IDs received from the RAN node.

[0263] In some examples, the AMF may additionally store, for TAI, CAG IDs supported by TAI (e.g., the at least one ‘home’ CAG IDs).

[0264] At S605, the further UE (UEx) triggers a registration procedure. UEx provides, to the AMF, a register request message. In some examples, UEx sends an NAS register request message to the AMF. The UEx may trigger the registration procedure in response to moving to a ‘new’ registration area (RA).

[0265] At S606, the AMF determines an RA for UEx (e.g., in response to receiving the register request message of S605). The determined RA comprises at least one TA. For example, the RA for UEx comprises at least TAI .

[0266] The AMF then filters a first list of CAG IDs based on: the data, and the at least one TA included in the RA of UEx. Each CAG ID in the first list identifies a CAG that UEx is permittedto access. In some examples, the AMF removes at least one CAG ID from the first list based on: the data, and the at least one TA included in the RA of UEx.

[0267] Before filtering, the first list of CAG IDs is obtained by the AMF. In some examples, the AMF receives the first list of CAG IDs from a network node. In some examples, the AMF receives the first list of CAG IDs from an operation and maintenance entity. The first list of CAG IDs comprises CAG IDs of CAGs that UEx is permitted (or allowed) to access across the PLMN.

[0268] For example, the AMF determines the RA for UEx to be: RA = (TAI, TA2).

[0269] The AMF identifies, using the data that has been stored, for each TA (e.g., TAI, TA2) of the RA, at least one CAG ID that is either: a supported CAG ID of TA1 / TA2 (e.g., a ‘home’ CAG ID), or a neighbour CAG ID of TA1 / TA2. The AMF then filters the first list of CAG IDs based on the identifying of the at least one CAG ID, so to obtain a filtered list of group identities. The filtering of the first list may comprise removing CAG IDs from the first list that were not identified as a home CAG ID or neighbour CAG ID. Stated differently, the AMF filters the first list of CAG IDs (that is PLMN wide) permitted for the UEx based on the data stored in S604. The AMF reduces the size of the first list of CAG IDs (before sending to UEx) by removing, from the full list of CAG IDs, those CAG IDs that were not identified as a home or a neighbour CAG ID for the RA of UEx.

[0270] The filtered list of CAG IDs is associated with UEx.

[0271] At S607a, the AMF provides, to UEx, the filtered list of CAG IDs. In some examples, the AMF sends an NAS register accept message to UEx including the filtered list of CAG IDs. In some examples, the AMF sends an NAS UE configuration update command to UEx including the filtered list of CAG IDs.

[0272] At S607b, the AMF provides, to the RAN node, the filtered list of CAG IDs. In some examples, the AMF sends an NGAP message to the RAN node including the filtered list of CAG IDs. The filtered list of CAG IDs may be comprised within a mobility restriction list IE.

[0273] The RAN node stores the filtered list of CAG IDs associated with UEx.

[0274] In some examples, S607a and S607b may be combined. For example, an NAS register accept message of S607a may be combined with the NGAP message of S607b.

[0275] At S608, the UEx stores the filtered list of CAG IDs. For example, the UEx may store the filtered list in non-volatile memory associated with UEx (e.g., in non-volatile memory of a universal subscriber identity module (USIM) of UEx).

[0276] An example to illustrate the process of FIG. 6 is as follows:- 5G gNB (RANI) supports TAI (cells 1,2, 3, ...,10). Cell 1 supports CAG 1, cell 2 supports CAG 2, cell 3 supports CAG 3. Cells 4 to 10 are not CAG cells.- 5G gNB (RAN2) supports TA2 (cells 11, 20). Cell 11 supports CAG 11, cell 12 supports CAG 12, cell 13 supports CAG 13. Cells 14 to 20 are not CAG cells.- CAG Cell 11 is neighbour of cell 1. Therefore TA2 is a neighbour of TAI.- CAG Cells 12, 13 are not neighbouring any cell of TAI.RANI sends to AMF1 : TAI supports CAG IDs = (CAG 1,2,3) + list of neighbour CAG IDs = CAG 11. (N.B. CAG 12, 13 are not measured by any UEs under the cells of TAI because cells 12, 13 are not neighbouring any cell of TAI)AMF1 stores the information received from RANI, per TA.

[0277] When the AMF 1 is to provide permitted CAG IDs to a UE (e.g., in response to a register accept message from the UE), the AMF1 knows the CAG IDs that are relevant to an RA of the UE (i.e., CAG IDs supported in a TA in the RA, and CAG IDs that are neighbouring a cell of a TA in the RA). In this manner, the list of CAG IDs provided to the UE has a reduced size (or minimum size).

[0278] It should be understood that the values provided above in the example are given as examples only to aid in the understanding of the disclosure.

[0279] FIG. 7 shows another example signalling and operations diagram between a user equipment and network nodes for determining a list of neighbour group identities.

[0280] In FIG. 7, the communications occur between a first UE (UE1), a second UE (UE2), a third UE (UE3), a further UE (UEx), a RAN node (e.g., NG-RAN node) and a core network node (e.g., AMF).

[0281] At S701, the O&M entity provides, to the RAN node, data (or information) related to a neighbour CAG ID. The neighbour CAG ID a CSG ID that is supported by a cell that neighbours at least one cell of a TA (e.g., TAI) supported by the RAN node.

[0282] The (neighbour) CAG ID is an example of a group identity.

[0283] In some examples, the O&M provides the data comprising the at least one neighbour CAG ID.

[0284] In some examples, O&M provides the data comprising a plurality of neighbour CAG IDs. In some examples, O&M provides the plurality of neighbour CAG IDs to the RAN node.

[0285] In some examples, the O&M entity configures the RAN node with the at least one neighbour CAG ID. In some examples, the O&M entity configures the RAN node with a data record comprising the at least one neighbour CAG ID.

[0286] At S702, the RAN node determines a data record for CAG IDs. The data record is associated with the RAN node. The RAN node determines the data record based on the data that has been received from the O&M entity. The determining of the data record may comprise: storing, in the data record associated with the RAN node, the at least one neighbour CAG ID based on the data from the O&M.

[0287] The RAN node stores the neighbour CAG ID in the data record. The RAN node may store the neighbour CAG ID in the data record per TA supported by the RAN node. Stated differently, the RAN node includes, in the data record, the neighbour CAG ID based on the TA. For example, each data entry (for a CAG ID) in the data record may have an associated TA. The TA associated with the CAG ID may be used as an index to store the CAG ID in the data record.

[0288] In some examples, the RAN node is configured with the data record comprising, for each supported TA, a list of neighbour CAG ID(s). In some examples, the RAN node is configured with, for each of its cells, a list of neighbour CAG ID(s). The RAN node then determines the lists for all cells of each TA to determine the data record comprising, for each supported TA, the list of neighbour CAG ID(s).

[0289] In this context, the data record is a store of data. In other examples, a database, a data store, a file, or a record, may be used instead of the data record. These terms may be used interchangeably in this context.

[0290] At S703, the RAN node provides, to the AMF, information related to the data record. In some examples, the information related to the data record comprises the neighbour CAG ID. In some examples, the information related to the data record comprises a list of neighbour CAG IDs per TA (from the data record).

[0291] In some examples, the information related to the data record may additionally comprise the at least one CAG ID that is supported in TAI (e.g., the at least one home CAG ID).

[0292] In some examples, the RAN node provides the data record (or the data of the data record), to the AMF. For example, the RAN node provides at least one data entry from the data record to the AMF.

[0293] In some examples, the RAN node sends the information to the AMF in an NGAP message. For example, the NGAP message may be a RAN configuration update message, or an NG setup request message.

[0294] An example of an NGAP message comprising the information related to the data record is shown in Table 4 below. In Table 4, the information is included in a parameter comprisingneighbour CAG IDs arranged in a list, per TA. The form / format of the information being included in a list is an example only. The information may be provided in any suitable format.Table 4: Example of parameters included in an NGAP RAN configuration update message, wherein the message has been extended to include a ‘Neighbour CAG Information List per TA’ (based on 3GPP TS 38.413 clause 9.2.6 4 RAN CONFIGURATION UPDATE).

[0295] For example, the RAN node may provide:Neighbour CAG Information List per TA = TAI [neighbour CAG ID 1, neighbour CAG ID 3, neighbour CAG ID 4]Neighbour CAG Information List per TA = TA2 [neighbour CAG ID2, neighbour CAG ID5, neighbour CAG ID6]

[0296] It should be understood that this is provided as an example only, to aid in the understanding of the disclosure.

[0297] At S704, the AMF stores data associated with the TAI, wherein the data comprises: for the TAI, the neighbour CAG ID. The storing of the data is based on the information received from the RAN node (in S703). In some examples, a plurality of CAG IDs associated with TAI are stored.

[0298] In some examples, the AMF stores data for a plurality of different TAs.

[0299] In some examples, the AMF stores, for TAI, a list of neighbour CAG IDs received from the RAN node.

[0300] In some examples, the AMF may additionally store, for TAI, CAG IDs supported by TAI (e.g., the at least one ‘home’ CAG IDs).

[0301] At S705, the further UE (UEx) triggers a registration procedure. UEx provides, to the AMF, a register request message. In some examples, UEx sends an NAS register request message to the AMF. The UEx may trigger the registration procedure in response to moving to a ‘new’ registration area (RA).

[0302] At S706, the AMF determines an RA for UEx (e.g., in response to receiving the register request message of S705). The determined RA comprises at least one TA. For example, the RA for UEx comprises at least TAI .

[0303] The AMF then filters a first list of CAG IDs based on: the data, and the at least one TA included in the RA of UEx. Each CAG ID in the first list identifies a CAG that UEx is permitted to access. In some examples, the AMF removes at least one CAG ID from the first list based on: the data, and the at least one TA included in the RA of UEx.

[0304] Before filtering, the first list of CAG IDs is obtained by the AMF. In some examples, the AMF receives the first list of CAG IDs from a network node. In some examples, the AMF receives the first list of CAG IDs from an operation and maintenance entity. The first list of CAG IDs comprises CAG IDs of CAGs that UEx is permitted (or allowed) to access across the PLMN.

[0305] For example, the AMF determines the RA for UEx to be: RA = (TAI, TA2).

[0306] The AMF identifies, using the data that has been stored, for each TA (e.g., TAI, TA2) of the RA, at least one CAG ID that is either: a supported CAG ID of TA1 / TA2 (e.g., a ‘home’ CAG ID), or a neighbour CAG ID of TA1 / TA2. The AMF then filters the first list of CAG IDs based on the identifying of the at least one CAG ID, so to obtain a filtered list of group identities. The filtering of the first list may comprise removing CAG IDs from the first list that were not identified as a home CAG ID or neighbour CAG ID. Stated differently, the AMF filters the first list of CAG IDs (that is PLMN wide) permitted for the UEx based on the data stored in S704. The AMF reduces the size of the first list of CAG IDs (before sending to UEx) by removing, from the full list of CAG IDs, those CAG IDs that were not identified as a home or a neighbour CAG ID for the RA of UEx.

[0307] The filtered list of CAG IDs is associated with UEx.

[0308] At S707a, the AMF provides, to UEx, the filtered list of CAG IDs. In some examples, the AMF sends an NAS register accept message to UEx including the filtered list of CAG IDs. In some examples, the AMF sends an NAS UE configuration update command to UEx including the filtered list of CAG IDs.

[0309] At S707b, the AMF provides, to the RAN node, the filtered list of CAG IDs. In some examples, the AMF sends an NGAP message to the RAN node including the filtered list of CAG IDs. The filtered list of CAG IDs may be comprised within a mobility restriction list IE.

[0310] The RAN node stores the filtered list of CAG IDs associated with UEx.

[0311] In some examples, S707a and S707b may be combined. For example, an NAS register accept message of S707a may be combined with the NGAP message of S707b.

[0312] At S708, the UEx stores the filtered list of CAG IDs. For example, the UEx may store the filtered list in non-volatile memory associated with UEx (e.g., in non-volatile memory of a universal subscriber identity module (USIM) of UEx).

[0313] It should be understood that one or more of the feature / steps of any of FIGS. 4 to 7 may not be performed in some examples, or may be performed in a different order.

[0314] One or more of the examples described above have the technical advantage that signalling overhead is reduced when providing, to a UE, group identities (e.g., CSG / CAG IDs) that are permitted to be accessed by the UE. This is because the size of the list is reduced to include (only) group identities that are relevant to the location (e.g., group identities associated with cells that are in close proximity to the UE).

[0315] When UEs are provided with a list of group identities, this list may comprise a large number of group identities and so the amount of data being transmitted to the UE may be large. However, this list is applicable across the whole of the PLMN, and so a location of the UE will likely mean that many of the group identities are not useful for the UE. In examples, the list of group identities is filtered down in size such that it (only) comprises group identities that are supported in a TA in the RA (of the UE) or neighbour a cell of a TA in the RA. Stated differently, a minimum number of group identities are provided to the UE, that are relevant to the current location of the UE, so that the minimum number of resources are needed for the signalling.

[0316] Furthermore, by reducing the size of the list of group identities, this also means that the transmitting of the list by the AMF is less frequent (e.g., fewer group identities in the list will statistically mean that there will be fewer updates compared to a list with more group identities). A reduction in the frequency of updating the list will also reduce radio signalling and reduce processing overhead.

[0317] FIG. 8 shows an example method flow performed by an apparatus. The apparatus may be a RAN node. For example, the RAN node may be 5G RAN node, gNB, NG-RAN.

[0318] At S801, the method comprises storing, in a data record associated with a RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least oneneighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node.

[0319] At S803, the method comprises: providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

[0320] FIG. 9 shows another example method flow performed by an apparatus. The apparatus may be a core network node. For example, the core network node may be an AMF.

[0321] At S901, the method comprises receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node.

[0322] At S903, the method comprises storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

[0323] FIG. 10 shows a schematic representation of non-volatile memory media 1000a (e.g. Blu-ray disc (BD), computer disc (CD) or digital versatile disc (DVD)) and 1000b (e.g. flash memory, solid state memory, universal serial bus (USB) memory stick) storing instructions and / or parameters 1002 which when executed by a processor allow the processor to perform one or more of the steps of the methods of FIGS. 8 to 9.

[0324] It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0325] The examples may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as nonlimiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0326] The examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by acombination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

[0327] The term “non-transitory”, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

[0328] As used herein, “at least one of the following:” and “at least one of: ” and similar wording, where the list of two or more elements are joined by “and”, or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0329] The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

[0330] As used herein, the terms “means for”, “means for performing operations including”, “means configured to perform operations including”, or “means configured to perform” (or similar) may be any means that are suitable for performing the feature(s). The “means” may be configured to perform one or more of the functions and / or method steps previously described. For example, the “means” may include one or more of: at least one processor, at least one memory, transceiver circuitry, antenna circuitry, etc. It should be understood that these are provided as non-limiting examples.

[0331] Alternatively, or additionally some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and / or method steps previously described. That circuitry may be provided in the base station and / or in the communications device.

[0332] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analogue and / or digital circuitry);(b) combinations of hardware circuits and software, such as:(i) a combination of analogue and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0333] This definition of circuitry applies to uses of the term “means” in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example integrated device. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0334] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

Claims1. A method performed by a radio access network, RAN, node, the method comprising: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to a core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity.

2. The method according to claim 1, wherein the storing of the at least one neighbour group identity in the data record is based on the TA that is related to the at least one neighbour group identity, and wherein the at least one neighbour group identity is associated with the TA within the data record.

3. The method according to claim 1 or claim 2, wherein the information related to the data record is provided, to the core network node, per TA supported by the RAN node.

4. The method according to any of claims 1 to 3, wherein method comprises: storing, in the data record, for the TA that is supported by the RAN node, a home group identity, wherein the home group identity comprises a group identity that is supported in a cell of the TA.

5. The method according to any of claims 1 to 4, wherein a neighbour group identify of the at least one neighbour group identity comprises a respective one of the following: an identity for a closed subscriber group, or an identity for a closed access group.

6. The method according to any of claims 1 to 5, wherein the determining comprises: receiving, from a user equipment in a first cell of the TA, a message comprising the at least one neighbour group identity, wherein the at least one neighbour group identity is associated with a second cell that neighbours the first cell of the TA; and storing, in the data record, the at least one neighbour group identity based on the TA.

7. The method according to any of claims 1 to 5, wherein the determining comprises: receiving, from an operations and maintenance entity, data related to the data record, wherein the data comprises the at least one neighbour group identity; and determining the data record based on the data.

8. The method according to claim 6, wherein the method further comprises: receiving, from a further user equipment in a third cell of a further TA supported by theRAN node, a further message comprising a further neighbour group identity that is associated with a fourth cell that neighbours the third cell of the further TA; and storing, in the data record, the further neighbour group identity based on the further TA.

9. The method according to claim 6 or claim 8, wherein at least one of the message, or the further message, is a radio resource control, RRC, message.

10. The method according to claim 6 or claim 8, further comprising: providing, by the RAN node to at least one user equipment, a trigger for a measurement report; and receiving, based on the providing of the trigger, at least one measurement report within an RRC message, the RRC message comprising at least one of: the at least one neighbour group identity or the further neighbour group identity.

11. The method according to claim 10, wherein the trigger is associated with an automatic neighbour relationship process.

12. The method according to claim 10 or claim 11, wherein the at least one measurement report is associated with mobility of the at least one user equipment.

13. The method according to any of claims 1 to 12, wherein the providing comprises: providing, to the core network node, a next generation application protocol, NGAP, message comprising the information related to the data record.

14. The method according to claim 13, wherein the NGAP message is at least one of: a RAN configuration update message, or an NG setup request message.

15. The method according to any of claims 1 to claim 14, wherein the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

16. The method according to any of claims 1 to 14, wherein the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

17. The method according to claim 16, wherein the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

18. The method according to claim 16, wherein the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

19. A method performed by a core network node, the method comprising: receiving, from a radio access network, RAN, node, information related to a data record that is associated with the RAN node, wherein the information comprises at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

20. The method according to claim 19, wherein the information related to the data record that is associated with the RAN node further comprises at least one home group identity, wherein a respective home group identity of the at least one home group identity comprises a group identity that is supported in a cell of the TA supported by the RAN node, and wherein the storing of the data further comprises: for the TA, storing the at least one home group identity.

21. The method according to claim 19 or claim 20, further comprising: receiving, from a user equipment, a registration request message; in response to the registration request message, determining a registration area, RA, for the user equipment;identifying, using the data that has been stored, for each TA of the RA, at least one group identity which is either: a home group identity of the TA, or a neighbour group identity of the TA; filtering a list of group identities that are permitted to be accessed by the user equipment based on the identifying, so to obtain a filtered list of group identities; and providing, to the user equipment, the filtered list of group identities.

22. The method according to any of claims 19 to 21, further comprising providing, to the RAN node, the filtered list of group identities.

23. The method according to claim 21, wherein the filtering comprises: obtaining the list of group identities associated with the user equipment; and removing, from the list of group identities, group identities that are not identified as either: a home group identity of the TA, or a neighbour group identity of the TA.

24. The method according to any of claims 19 to 23, wherein the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

25. The method according to any of claims 19 to 23, wherein the RAN node and the at least one neighbour group identity are associated with different radio access technologies, RATs.

26. The method according to claim 25, wherein the RAN node is a 5G node and the at least one neighbour group identity is associated with at least one 4G RAN node.

27. The method according to claim 25, wherein the RAN node is a 4G node and the at least one neighbour group identity is associated with at least one 5G RAN node.

28. An apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform any of the methods of claims 1 to 18.

29. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform any of the methods of claims 1 to 18.

30. An apparatus comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform any of the methods of claims 19 to 27.

31. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform any of the methods of claims 19 to 27.

32. A system comprising: a radio access network, RAN, node; and a core network node, wherein the RAN node comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the RAN node to perform: storing, in a data record associated with the RAN node, at least one neighbour group identity, wherein each neighbour group identity of the at least one neighbour group identity comprises a respective group identity that is supported in a respective cell that neighbours at least one cell of a tracking area, TA, supported by the RAN node; and providing, to the core network node, information related to the data record, wherein the information comprises the at least one neighbour group identity, and wherein the core network node comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the core network node to perform: receiving, from the radio access network, RAN, node, information related to the data record that is associated with the RAN node, wherein the information comprises the at least one neighbour group identity; and storing data associated with the TA, wherein the data comprises: for the TA, the at least one neighbour group identity.

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