WO2025171550A1

WO2025171550A1 - Apparatus, method and computer program

Info

Publication number: WO2025171550A1
Application number: PCT/CN2024/077231
Authority: WO
Inventors: Basavaraj KIRAGI; Philippe Godin; Ling Yu; Yuan Sheng QIAN
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2024-02-15
Filing date: 2024-02-15
Publication date: 2025-08-21
Anticipated expiration: 2026-08-15

Abstract

There is provided an apparatus comprising means for receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and means for providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

Description

Apparatus, method and computer program

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to handover from a source network to a target femto network with CSG ID based access control in the source network.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided, for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email) , text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services, and access to a data network system, such as the Internet.

In a wireless communication system, at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN) , satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN) . Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device 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 users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) (3G radio) . Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP) . Other examples of communication systems include 5G-Advanced (NR Rel-18 and beyond) and 6G.

Summary

In a first aspect there is provided an apparatus comprising means for receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and means for providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

The apparatus may comprise means for generating the measurement report comprising the indication of the at least one group identifier.

In a second aspect there is provided an apparatus for a source network comprising means for receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network and means for performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.

Means for receiving the indication of the group identifier may comprise means for receiving a measurement report from the user equipment, the measurement report comprising the group identifier.

Means for performing, at the source network, access control for the user equipment in the target network may comprise means for providing a handover required message to a function of the source network, the handover required message comprising an indication of the group identifier.

The apparatus may comprise a radio access node and the function of the source network may comprise an access management function or a mobility management function.

Means for performing, at the source network, access control for the user equipment in the target network may comprise means for performing, at the apparatus, a check whether the received group identifier belongs to a list of group identifiers allowed for the user equipment in the target network.

The apparatus may further comprise means for determining, based on a result of the check, whether triggering a handover of the user equipment to the target network is permitted.

The apparatus may be a radio access node and wherein the apparatus may comprise means for receiving the list of group identifiers allowed for the user equipment from an access management function or a mobility management function of the source network.

The list of group identifiers allowed for the user equipment may be received from the access management function or the mobility management function of the source network within mobility restriction list information.

Means for receiving the indication of the group identifier may comprise means for receiving a handover required message indicating a handover of the user equipment to the target network is to be performed, the handover required message comprising the indication of the group identifier.

Means for performing, at the source network, access control for the user equipment in the target network may comprise means for performing at the apparatus a check whether the indication of the group identifier received in the handover required message belongs to a list of group identifiers allowed for the user equipment in the target network.

The apparatus may further comprise means for determining, based on a result of the check, whether to continue or to fail the handover of the user equipment to the target network.

The apparatus may comprise an access management function or a mobility management function and the handover required message may be received from a radio access node of the source network.

The source network may comprise a 5G network and the target network may be a 4G network.

The source network may comprise a 4G network and the target network may comprise a 5G network.

In a third aspect there is provided a method comprising receiving, at an apparatus, at least one group identifier from an access node of a target network, when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

The method may comprise generating the measurement report comprising the indication of the at least one group identifier.

In a fourth aspect there is provided a method comprising receiving, at a node of a source network, from a user equipment registered with a source network, an indication of a group identifier received at a user equipment from an access node of a target network and performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.

Receiving the indication of the group identifier may comprise receiving a measurement report from the user equipment, the measurement report comprising the group identifier.

Performing, at the source network, access control for the user equipment in the target network may comprise providing a handover required message to a function of the source network, the handover required message comprising an indication of the group identifier.

The method may comprise a radio access node and the function of the source network may be an access management function or a mobility management function.

Performing, at the source network, access control for the user equipment in the target network may comprise performing, at the apparatus, a check whether the received group identifier belongs to a list of group identifiers allowed for the user equipment in the target network.

The method may further comprise determining, based on a result of the check, whether triggering a handover of the user equipment to the target network is permitted.

The apparatus may be a radio access node and the method may comprise receiving the list of group identifiers allowed for the user equipment from an access management function or a mobility management function of the source network.

Receiving the indication of the group identifier may comprise receiving a handover required message indicating a handover of the user equipment to the target network is to be performed, the handover required message comprising the indication of the group identifier.

Performing, at the source network, access control for the user equipment in the target network may comprise performing at the apparatus a check whether the indication of the group identifier received in the handover required message belongs to a list of group identifiers allowed for the user equipment in the target network.

The method may further comprise determining, based on a result of the check, whether to continue or to fail the handover of the user equipment to the target network.

The source network may comprise a 5G network and the target network may comprise a 4G network.

In a fifth aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform receiving at least one group identifier from an access node of a target network, when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

In a sixth aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving at least one group identifier from an access node of a target network, when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

The apparatus may be caused to perform generating the measurement report comprising the indication of the at least one group identifier.

In a seventh aspect there is provided an apparatus for a source network, the apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network and performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.

In an eighth aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus for a source network, cause the apparatus to perform at least the following receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network; and performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.

The apparatus may be caused to perform determining, based on a result of the check, whether triggering a handover of the user equipment to the target network is permitted.

The apparatus may be a radio access node and wherein the apparatus may be caused to perform receiving the list of group identifiers allowed for the user equipment from an access management function or a mobility management function of the source network.

Performing, at the source network, access control for the user equipment in the target network may comprise performing at the apparatus a check whether the indication of the closed of group identifiers allowed for the user equipment in the target network.

The apparatus may be caused to perform determining, based on a result of the check, whether to continue or to fail the handover of the user equipment to the target network.

In an aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspect.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example 5GS communication system;

Figure 2 shows a schematic diagram of an example mobile communication device;

Figure 3 shows a schematic diagram of an example control apparatus;

Figure 4 shows a flowchart of a method according to an example embodiment;

Figure 5 shows a flowchart of a method according to an example embodiment;

Figure 6 shows a schematic diagram of a mobility architecture according to an example embodiment;

Figure 7 shows a signalling and operations diagram according to an example embodiment;

Figure 8 shows a signalling and operations diagram according to an example embodiment.

Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figure 1, Figure 2 and Figure 3 to assist in understanding the technology underlying the described examples.

An example of a suitable communications system may employ a 5G or NR architecture . The network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation NodeBs (gNBs) . Changes to the network architecture may depend on the need to support various radio technologies and finer Quality of Service (QoS) support, and some on-demand requirements, for e.g., QoS levels to support Quality of Experience (QoE) for a user. Network aware services and applications, and service and application aware networks may also bring changes to the architecture. The changes are reflected in Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use Multiple Input –Multiple Output (MIMO) antennas, many more base stations or nodes than LTE (a so-called small cell concept) , including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications, this may mean node operations are to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of LTE or may even be non-existent.

Figure 1 shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal) , a 5G radio access network (5GRAN) 104, a 5G core network (5GCN) 106, one or more internal or external application functions (AF) 108 and one or more data networks (DN) 110.

An example 5G core network (CN) comprises functional entities. The 5GCN 106 may comprise one or more Access and mobility Management Functions (AMF) 112, one or more session management functions (SMF) 114, an authentication server function (AUSF) 116, a Unified Data Management (UDM) 118, one or more user plane functions (UPF) 120, a Unified Data Repository (UDR) 122 and/or a Network Exposure Function (NEF) 124. The UPF is controlled by the SMF (Session Management Function) that receives policies from a PCF (Policy Control Function) .

The CN is connected to a UE via the Radio Access Network (RAN) . The 5GRAN may comprise one or more gNodeB (gNB) Distributed Unit (DU) functions connected to one or more gNodeB (gNB) Centralized Unit (CU) functions. The RAN may comprise one or more access nodes.

A User Plane Function (UPF) referred to as PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the DN and the tunnels established over the 5G towards the UE (s) exchanging traffic with the DN.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise 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) , personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VoIP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , smart devices, wireless customer-premises equipment (CPE) , or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email) , text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts, and other information.

A mobile device is typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 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 data processing, storage and other relevant components can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2, transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 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.

Figure 3 shows an example of a control apparatus 300 for a communication system, for example, to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or Serving Gateway (S-GW) or Packet Data Network Gateway (P-GW) , or a core network function such as AMF/SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

For release-19 of 3GPP, a study item on Femto support in 5G has been approved. In LTE, Femto are also referred to as HeNB or 4G femtos. A Closed Subscriber Group (CSG) is a group of subscribers who are permitted/allowed to access one or more CSG cells of the PLMN identified by CSG ID (s) . A CSG cell is a cell broadcasting one or several CSG IDs. Each CSG is identified by a corresponding group identity (ID) (or identifier) for the CSG (e.g., a closed group identifier, e.g., CSG-ID) . 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 is a 27 bitstring (bitstring having a length of 27 bits) . A base station hosting CSG cells is called a HeNB or 4G/LTE Femto base station. CSG membership of a UE is configured in the user subscription data and on the UE. If a UE tries to connect to a CSG cell, the network (e.g., MME of the network) checks whether the UE is allowed to do so considering the subscription data. Herein, a base station capable of hosting CSG cells may also be referred to as an access node.

Several 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 to introduce 5G Home gNB (HgNB) also called 5G femtos in release 19. In one mode of HgNB cells called closed access mode, only certain subscribers are allowed to access the cell, similar to HeNBs. To enable this mode of operation for a HgNB cell, 3GPP envisions to reuse the CAG concept which was introduced in 5G in 3GPP release 16 for NPN.

In 5G, a Closed Access Group (CAG) is a group of subscribers who are permitted/allowed to access one or more CAG cells associated to the CAG ID. Each CAG is identified by a corresponding group identity (or identifier) for the CAG (e.g., a closed group identifier, e.g., CAG-ID) . A CAG cell is a cell broadcasting one or several CAG IDs. The CAG concept is like the CSG concept in LTE, but was originally introduced in the context of PNI-NPNs to prevent UE (s) , which are not allowed to access the NPN via the associated cell (s) , from automatically selecting and accessing the associated CAG cell (s) . CAG based access control was introduced in 3GPP Release-16. 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 identifier (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 ID is a 32 bitstring (bitstring having a length of 32 bits) . Herein, an access node capable of hosting CAG cells may also be referred to as a base station.

When introducing the concept of 5G Femto in release 19, mobility from HgNB cells possibly using CAG cells to HeNBs, possibly using CSG cells, should be considered. e.g., an operator might introduce 5G Femto gradually on top of an existing LTE Femto deployment.

The following is related to handover from a source system to a target CSG cell. Before allowing access of a subscriber to the target CSG cell, access control must be performed to allow the UE or not allow the UE access.

The target MME is connected to the target HeNB and therefore should know information about CSG IDs support of the target HeNBs. However, solutions relying on a target system to perform the access control may have the problem that when the access is denied, extraneous signalling is exchanged. This extraneous signalling introduces delay in the handover process since another mobility solution must be found by the source side after this failed attempt (e.g,, denial of access) .

Figure 4 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus, for example, at a UE.

In 401, the method comprises receiving, at the apparatus, at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types.

In 402, the method comprises providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier. The method may include generating the measurement report comprising the indication of the at least one group identifier prior to providing the measurement report to the source network.

The term group identifier may be a closed group identifier. A closed group identifier identifies a group of subscribers who are permitted/allowed to access one or more cells associated to the closed group identifier. A CSG ID or a CAG ID, as discussed above, are examples of a closed group identifier.

Figure 5 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus for a source network. The apparatus may comprise a network function, such an AMF or mobility management function (e.g., MME) , or a radio access node, such as gNB or eNB.

In 501, the method comprises receiving, at a node of the source network, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network.

In 502, the method comprises performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.

The term group identifier may be a closed group identifier and may be a CSG ID or a CAG ID as discussed above.

The source network may comprise a 5G network. The target network may comprise a 4G network. In this case, the group identifier may comprise a CSG ID.

The source network may comprise a 4G network and the target network may comprise a 5G network. In this case, the group identifier may comprise a CAG ID.

The target network may comprise a femto network.

Performing, at the source network, access control for the user equipment in the target network may comprise performing at the apparatus a check whether the received indication of the group identifier belongs to a list of group identifiers allowed for the user equipment in the target network.

The methods described above may provide solutions to enable UE mobility from source 5G system (e.g., from macro 5G cell or from 5G femto cell) to target 4G femto cells with CSG ID based access control in the source 5G system.

A 5G source system may be provided with relevant CSG ID related access rights in order to enable the source 5G system to perform the access control for the involved end user based on the CSG ID of the target cell.

A method as described with reference to Figure 5 may be performed at an AMF or mobility management function of the source network. The method may comprise receiving a handover required message indicating a handover of the user equipment to the target network is to be performed, the handover required message comprising the indication of the group identifier.

The method may further comprise determining, based on a result of the check whether the indication of the group received in the handover required message identifier belongs to the list of group identifiers allowed for the user equipment in the target network, whether to continue or to fail the handover of the user equipment to the target network.

The handover required message may be received at the apparatus from a radio access node of the source network.

For example, a source AMF (i.e., AMF in the source network) may be the entity in a source 5G system which performs access control for a UE based on CSG ID, assuming the source AMF can access the list of group identifiers allowed for the user equipment in the target network.

In this example embodiment, at handover preparation, the UE sends the CSG ID of the target CSG cell within the measurement report message to the source NG-RAN and the source NG-RAN includes this target cell CSG ID in the NGAP Handover Required towards the AMF. This provides an example of an apparatus receiving a measurement report from the user equipment, the measurement report comprising the group identifier and providing a handover required message to a function of the source network, the handover required message comprising an indication of the group identifier.

The AMF performs the access control using this received CSG ID. This provides an example of an apparatus performing, at the source network, access control for the user equipment in the target network based on the group identifier.

Figure 6 shows an example mobility scenario from 5GS to 4GS. The UE is attached to (i.e., registered with) the 5GS. The UE receives SIB1 (which includes CSG ID) from an eNB of the 4GS. The UE provides a measurement report including the CSG ID to NG-RAN of the 5GS, where access control is performed in the AMF of the 5GS. If access control is successful, the AMF can then continue the handover (HO) procedure via the MME of 4GS.

Figure 7 shows a signalling and operations diagram according to an example embodiment. In step 0, the UE registers to the 5GS network (e.g., using existing signalling) and is in RRC CONNECTED mode.

In step 1, the UE enters into the proximity of cells of the 4GS and starts receiving the SIB1 from eNB. SIB1 has CSG ID in it. This is an example of receiving, at a user equipment, at least one group identifier from an access node of a target network when the user equipment is registered with a source network,

In step 2, the UE sends measurement reports including the measurement result of neighboring 4G CSG cells to the NG RAN (e.g., radio access node of the NG RAN) . This is an example of the UE providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

In step 3, the NG-RAN receives the measurement report/srelated to the neighboring candidate target 4G CSG cells from the UE, with the CSG ID included in the measurement report/s. The source NG-RAN includes the received CSG ID into a handover required message (e.g., a NGAP Handover Required message) towards an AMF. This is an example of an apparatus receiving a measurement report from the user equipment, the measurement report comprising the group identifier and providing a handover required message to a function of the source network, the handover required message comprising an indication of the group identifier.

In step 4, AMF compares the CSG-ID received from NG-RAN in the handover required message (e.g., NGAP Handover Required message) with the allowed CSG ID list of/associated with the UE. The AMF performs access control using the CSG ID and accessing the database giving the access rights associated with CSG ID for this UE. This is an example of performing at the apparatus a check whether the indication of the group identifier that is received in the handover required message belongs to a list of group identifiers allowed for the user equipment in the target network.

In step 5, existing signalling shall be followed as per the 3GPP Specification. If it is determined, based on a result of the check, to continue the handover, signalling to continue the HO procedure is performed. If it is determined, based on the results of the check to fail the HO, signalling to inform the source access node of the failure is performed.

A method as described with reference to Figure 5 may be performed at a RAN of the source network and may comprise receiving a measurement report from the user equipment, the measurement report comprising the group identifier.

An illustrative example of a measurement report according to an embodiment is provided below.

Performing, at the source network, access control for the user equipment in the target network may comprises providing a handover required message to a function (e.g., AMF or MME) of the source network, the handover required message comprising an indication of the group identifier, as described above.

Alternatively, or in addition, a check whether the indication of the group identifier belongs to a list of group identifiers allowed for the user equipment in the target network may be performed at the source RAN node.

The method may comprise determining, based on a result of the check, whether triggering a handover of the user equipment to the target network is permitted.

The method may comprise receiving the list of group identifiers allowed for the user equipment at the source RAN node from an access management function or a mobility management function of the source network.

The list of group identifiers allowed for the user equipment may be received, at the source RAN node from the access management function or the mobility management function of the source network, within a mobility restriction list information (e.g., information of a mobility restriction list) .

For example, the source NG-RAN may be the entity in the source 5G system which performs the access control for the end user based on a mobility restriction list (e.g., in a UE context) which has been extended with group identifier information earlier provided by the AMF. This provides an example of a RAN performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the list of group identifiers allowed for the user equipment is received from an access management function of the source network within mobility restriction list information.

In an example embodiment, when a UE gets RRC connected in the source 5G system, the AMF sends the Mobility Restriction List to the source NG-RAN as part of the UE context. This Mobility Restriction list may be extended to additionally include the allowed CSG IDs for this UE which the AMF has derived from accessing relevant database.

Later, at handover preparation, the UE sends the target CSG cell CSG ID in the measurement report to the source NG-RAN and the source NG-RAN performs the access control based on the above earlier received Extended Mobility Restriction List.

In step 0, the UE registers to the 5GS network (e.g., using existing signalling) and is in RRC CONNECTED mode.

In step 1, when the UE enters 5G RRC connected state, the NG-RAN receives the 5G UE context including the 5G Mobility Restriction List (MRL) . This 5G UE context is typically received from AMF in the NGAP INITIAL CONTEXT SETUP REQUEST message or the HANDOVER REQUEST message. In an example embodiment, the 5G MRL is newly extended with an allowed CSG ID list (e.g., list of group identifiers allowed for the user equipment) which is stored by NG-RAN node when receiving the NGAP INITIAL CONTEXT SETUP REQUEST OR HANDOVER REQUEST. This is an example of an apparatus receiving the list of group identifiers allowed for the user equipment from the access management function of the source network within mobility restriction list information.

In step 2, the NG-RAN receives the 5G measurement report/smessage from the UE, the measurement report/sincluding CSG ID. This is an example of an apparatus receiving a measurement report from the user equipment, the measurement report comprising the group identifier.

In step 3, using the extended MRL (which includes CSG ID) present at the source NG-RAN, the source NG-RAN performs access control. For example, the NG-RAN may perform a check (i.e., determine) whether the received group identifier belongs to a list of group identifiers allowed for the user equipment in the target network.

In step 4, existing signalling shall be followed as per the 3GPP Specification. For example, if it is determined that trigger of a HO of the UE to the target network is permitted, the RAN node may send a handover required message to a network function.

Both embodiments above apply for both monolithic RAN node and split RAN node. For example, when a gNB is split between gNB-CU and gNB-DU, the actions above may apply to gNB-CU.

The embodiments described with reference to Figures 6, 7 and 8 relate to an example embodiment in which the source network comprises a 5G network, the target network comprises a 4G network, and the group identifier is CSG ID.

Methods as described with reference to Figures 4 and 5 are also applicable when the source network comprises a 4G network and the target network comprises a 5G network. In this example embodiment in which the target network comprises a 5G network, the group identifier comprises a CAG ID. In this case, on receiving the CAG (Closed Access Group) identifier, the UE provides a measurement report comprising the CAG identifier to an eNB of a source network. The eNB may perform access control by performing a check whether the received CAG identifier belongs to a list of CAG identifiers allowed for the user equipment in the target network and may, based on a result of the check, determine whether triggering a handover of the user equipment to the target network is permitted. The eNB may receive the list of CAG identifiers allowed for the user equipment from a mobility management function of the source network. The list of CAG identifiers may be received from the mobility management function of the source network within the mobility restriction list information.

Alternatively, or in addition, the eNB may perform access control by providing a handover required message to a mobility management function of the source network. The mobility management function receives the handover required message and performs a check whether the indication of the CAG identifier that is received in the measurement report belongs to a list of CAG identifiers allowed for the user equipment in the target network.

Illustrative examples for extending a 5G mobility restriction list are provided in the tables below. The underlined sections show the extension to the mobility restriction list.

Illustrative example 1 shows an allowed PNI-NPN List (TS 38.413 Clause 9.3.3.45) which has been extended with an allowed CSG list per PLMN. The CSG ID in illustrative example 1 is a bitstring having a length of 27 bits.

Illustrative Example 1

Illustrative example 2 shows an example of extending the 5G MRL (with the extended parts indicated by being underlined) . The IE shown in illustrative example 2 defines roaming or access restrictions for subsequent mobility action for which the NG-RAN provides information about the target of the mobility action towards the UE, e.g., handover, or for SCG selection during dual connectivity operation or for assigning proper RNAs. NG-RAN behaviour upon receiving this IE is specified in TS 23.501.

The MRL includes 4G mobility information, the 4G mobility information comprises an allowed CSGList per PLMN and the CSG ID is a bitstring of length 27.

Illustrative Example 2

An apparatus may comprise means for receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types and means for providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.

The apparatus may comprise a user equipment as described with reference to Figure 2, be the user equipment or be comprised in the user equipment or a chipset for performing at least some actions of/for the user equipment.

An apparatus may comprise means for receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network, and means for performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types. The source network and the target network being of different radio access technology types refers to the source network and the target network being of or implementing different radio access technologies.

The apparatus may comprise an access node of a network, such as gNB, a network function such as AMF or MME, be the access node or network function or be comprised in the access node or network function or a chipset for performing at least some actions of/for the access node or network function.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems such as 6G networks or 5G-Advanced networks. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein 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.

As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” 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 the elements.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure 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 the disclosure is not limited thereto. While various aspects of the disclosure 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 non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

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 analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog 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 a mobile phone or server, to perform various functions) and

I 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. ”

This definition of circuitry applies to all uses of this term 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 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 server, a cellular network device, or other computing or network device.

The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures 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. The physical media is a non-transitory media. 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) .

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 comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) , application specific integrated circuits (ASIC) , FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. 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 of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

An apparatus comprising:

means for receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types; and

means for providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.
The apparatus of claim 1, further comprising:

means for generating the measurement report comprising the indication of the at least one group identifier.
An apparatus for a source network, the apparatus comprising:

means for receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network; and

means for performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.
The apparatus according to claim 3, wherein the means for receiving the indication of the group identifier comprises means for receiving a measurement report from the user equipment, the measurement report comprising the group identifier, and wherein the means for performing, at the source network, access control for the user equipment in the target network comprises means for providing a handover required message to a function of the source network, the handover required message comprising the indication of the group identifier.
The apparatus according to claim 4, wherein the apparatus comprises a radio access node and wherein the function of the source network is an access management function or a mobility management function.
The apparatus according to claim 3, wherein the means for receiving the indication of the group identifier comprises means for receiving a measurement report from the user equipment, the measurement report comprising the group identifier, and wherein the means for performing, at the source network, access control for the user equipment in the target network comprises means for performing, at the apparatus, a check whether the received group identifier belongs to a list of group identifiers allowed for the user equipment in the target network.
The apparatus according to claim 6 further comprising:

means for determining, based on a result of the check, whether triggering a handover of the user equipment to the target network is permitted.
The apparatus according to claim 6 or claim 7 wherein the apparatus is a radio access node, and wherein the apparatus comprises means for receiving the list of group identifiers allowed for the user equipment from an access management function or a mobility management function of the source network.
The apparatus according to claim 8 wherein the list of group identifiers allowed for the user equipment is received from the access management function or the mobility management function of the source network within mobility restriction list information.
The apparatus according to claim 3, wherein the means for receiving the indication of the group identifier comprises

means for receiving a handover required message indicating a handover of the user equipment to the target network is to be performed, the handover required message comprising the indication of the group identifier; and wherein the means for performing, at the source network, access control for the user equipment in the target network comprises means for performing at the apparatus a check whether the indication of the group identifier received in the handover required message belongs to a list of group identifiers allowed for the user equipment in the target network.
The apparatus according to claim 10, further comprising means for determining, based on a result of the check, whether to continue or to fail the handover of the user equipment to the target network.
The apparatus according to claim 10 or claim 11, wherein the apparatus comprises an access management function or a mobility management function, and wherein the handover required message is received from a radio access node of the source network.
The apparatus of any preceding claim wherein the source network comprises a 5G network and the target network comprises a 4G network.
The apparatus of any preceding claim wherein the source network comprises a 4G network and the target network comprises a 5G network.
A method comprising:

receiving, at an apparatus, at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network e are of different radio access technology types; and

providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.
The method of claim 15, further comprising generating the measurement report comprising the indication of the at least one group identifier.
A method comprising:

receiving, at a node of a source network, from a user equipment registered with a source network, an indication of a group identifier received at a user equipment from an access node of a target network; and

performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.
An apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform:

receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types; and

providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.
An apparatus for a source network comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform:

receiving from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network; and

performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.
A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following:

receiving at least one group identifier from an access node of a target network when the apparatus is registered with a source network, wherein the source network and the target network are of different radio access technology types; and

providing a measurement report relating to the access node of the target network to the source network, the measurement report comprising an indication of the at least one group identifier.
A computer readable medium comprising instructions which, when executed by an apparatus for a source network, cause the apparatus to perform at least the following:

receiving, from a user equipment registered with the source network, an indication of a group identifier received at the user equipment from an access node of a target network; and

performing, at the source network, access control for the user equipment in the target network based on the group identifier, wherein the source network and the target network are of different radio access technology types.