Emergency network slice support

Abstract

Examples of the disclosure relate to emergency network slice support. In examples of the disclosure a network node is arranged to provide an indication of network slices configured for support of an emergency call, to at least one core network node and receive an emergency network slice configuration of at least one network slice from the at least one core network node. The at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

Description

[0001] TITLE

[0002] Emergency Network Slice Support

[0003] TECHNOLOGICAL FIELD

[0004] Examples of the disclosure relate to emergency network slice support.

[0005] BACKGROUND

[0006] In communication networks user equipments can be used to make emergency calls. A network node can provide support for emergency calls either directly or by through fallback mechanisms towards E-UTRA or other suitable networks. The support of emergency calls by the network node can be broadcast by a network node in system information or any other suitable signalling.

[0007] BRIEF SUMMARY

[0008] According to various, but not necessarily all, examples of the disclosure there may be provided a network access node comprising:

[0009] at least one processor;

[0010] and at least one memory storing instructions that, when executed by the at least one processor, cause the network node at least to perform:

[0011] providing an indication of network slices configured for support of an emergency call, to at least one core network node; and

[0012] receiving an emergency network slice configuration of at least one network slice from the at least one core network node where the at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

[0013] The processor and memory may be further configured to perform:

[0014] providing, to the core network node, an indication of preference associated with the indicated network slices configured for support of an emergency call.

[0015] The indicated network slices may be indicated for at least one of:

[0016] respective cells;

[0017] respective tracking areas.

[0018] The received emergency network slice configuration may be received for at least one of:

[0019] respective cells;

[0020] respective tracking areas. The indication of network slices configured for support of an emergency call may comprise one or more of:

[0021] network slice support of neighboring tracking areas;

[0022] network slice support of neighboring cells;

[0023] historical information relating to mobility statistics;

[0024] emergency network slice support for neighboring tracking areas for respective core network nodes;

[0025] emergency network slice support for neighboring cells for respective core network nodes.

[0026] The processor and memory may be further configured to perform:

[0027] receiving an emergency network slice configuration from multiple core network nodes; and

[0028] selecting a preferred network slice for emergency calls for respective core network nodes.

[0029] The processor and memory may be further configured to perform:

[0030] receiving an emergency network slice configuration from multiple core network nodes; and

[0031] selecting a preferred network slice for emergency call to be used for at least one of:

[0032] respective cells;

[0033] respective tracking areas.

[0034] The processor and memory may be further configured to perform:

[0035] broadcasting in a cell at least one of:

[0036] one or more network slices preferred for emergency calls in the cell;

[0037] one or more network slices supported for emergency calls in the cell;

[0038] one or more network slices preferred for emergency calls in the tracking area of the cell;

[0039] one or more network slices supported for emergency calls in the tracking area of the cell.

[0040] The processor and memory may be further configured to perform:

[0041] receiving an indication of whether or not emergency calls should be enabled. The processor and memory may be further configured to perform:

[0042] receiving, from a user equipment (UE) located in a cell, a connection request; determining that no core network node has yet been assigned for this UE; determining the preferred network slice for emergency calls for the current cell or tracking area comprising the cell;

[0043] selecting a core network node to send the request to, based on at least the determined preferred network slice for emergency calls.

[0044] The processor and memory may be further configured to perform:

[0045] receiving, from a user equipment (UE) located in a cell, a connection request; determining the preferred network slice for emergency calls for the current cell or current tracking area comprising the cell;

[0046] determining the identity of a core network node which has already been assigned for this UE and that the assigned core network node does not support the determined preferred network slice for emergency calls; and

[0047] based on the determining that the core network node does not support the determined preferred network slice, sending a message to the core network node comprising relocation information.

[0048] The processor and memory may be further configured to perform:

[0049] determining that a received connection request from a UE is for an emergency call setup and that the UE has an assigned core network node which does not support the preferred network slice for current cell or tracking area of the UE;

[0050] based on the determining, sending a message to the core network node comprising relocation information.

[0051] The relocation information may comprise at least one of:

[0052] a request to relocate the UE to another core network node;

[0053] an indication of a preferred network slice for emergency calls;

[0054] an indication of a supported network slice for emergency calls;

[0055] an identity of another core network node to which the UE is requested to be relocated.

[0056] The processor and memory may be further configured to perform:

[0057] determining that a received connection request from a UE is for an emergency call setup and that the UE has an assigned core network node which does not support the preferred network slice for emergency calls for the current cell or tracking area; based on the determining, sending a message to another core network node, the message comprising at least one:

[0058] a request to fetch UE context from the assigned core network node;

[0059] an indication of a preferred network slice for emergency calls;

[0060] an indication of a supported network slice for emergency calls;

[0061] an identity of the assigned core network node from which the UE context is to be fetched.

[0062] The processor and memory may be further configured to perform:

[0063] exchanging information with one or more neighboring network access nodes wherein the exchanged information comprises at least one:

[0064] indication of supported network slices for emergency calls for respective cells; indication of supported network slices for emergency calls for respective tracking areas;

[0065] indication of preferred network slices for emergency calls for respective cells; indication of preferred network slices for emergency calls for respective tracking areas.

[0066] The processor and memory may be further configured to perform:

[0067] sending the exchanged information from the neighboring network access nodes to the core network node.

[0068] According to various, but not necessarily all, examples of the disclosure there may be provided a method comprising:

[0069] providing an indication of network slices configured for support of an emergency call, to at least one core network node; and

[0070] receiving an emergency network slice configuration of at least one network slice from the at least one core network node where the at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

[0071] According to various, but not necessarily all, examples of the disclosure there may be provided a core network node comprising:

[0072] at least one processor;

[0073] and at least one memory storing instructions that, when executed by the at least one processor, cause the core node at least to perform: receiving an indication of network slices configured for support of an emergency call, from a network access node;

[0074] configuring at least one network slice from the network access node for emergency calls wherein the configured network slices comprise at least one of the indicated supported network slices; and

[0075] providing the emergency network slice configuration of the at least one network slice to the network access node.

[0076] The processor and memory may be further configured to enable the core network node to:

[0077] receive, from the network access node, an indication of preference associated with the indicated slices configured for support of an emergency call;

[0078] select the emergency network slice to be configured for emergency calls based, at least in part, on the indication of preference.

[0079] The at least one network slice that is configured for emergency call may be selected based, at least in part, on the network slices supported by the core network node.

[0080] A list of network slices supported by the core network node may be received from an operations and maintenance system

[0081] The processor and memory may be configured to enable the core network node to determine if emergency calls are allowed; and

[0082] configure the network slice for emergency calls if emergency calls are allowed; or

[0083] provide an indication to the network access node that emergency calls are not allowed if emergency calls are not allowed.

[0084] Receiving the indication of network slices configured for support of an emergency call from the network access node may further comprise at least one of the following:

[0085] receiving the indication of network slices configured for support of an emergency call for respective cells;

[0086] receiving the indication of network slices configured for support of an emergency call for respective tracking areas. Configuring at least one network slice from the core network node for emergency calls wherein the configured network slices are at least one of the indicated supported network slices may further comprise at least one of the following:

[0087] configuring the at least one network slice for respective cells;

[0088] configuring the at least one network slice for respective tracking areas.

[0089] The processor and memory may be configured to enable the core network node to provide an indication of whether or not emergency calls are enabled for a given cell or tracking area.

[0090] The processor and memory may be further configured to enable the core network node to perform:

[0091] receiving a connection message associated with a UE from a network access node, the connection message comprising at least one of:

[0092] an indication of one or more network slices configured for support of an emergency call in the cell of the UE;

[0093] an indication of one or more network slices configured for support of an emergency call in the tracking area of the UE;

[0094] an indication of one or more network slices preferred for support of an emergency call in the cell of the UE;

[0095] an indication of one or more network slices preferred for support of an emergency call in the tracking area of the UE;

[0096] a request for relocation of the UE context to another core network node; an indication of at least one other core network node onto which the UE context can be relocated;

[0097] determining, based at least in part on the connection message, to relocate the UE context to another core network node; and

[0098] sending a request for relocation of UE context at least to one of; the network access node or the another core network node.

[0099] According to various, but not necessarily all, examples of the disclosure there may be provided a method comprising:

[0100] receiving an indication of network slices configured for support of an emergency call, from a network access node;

[0101] configuring at least one network slice from the network access node for emergency calls wherein the configured network slices comprise at least one of the indicated supported network slices; and providing the emergency network slice configuration of the at least one network slice to the network access node.

[0102] According to various, but not necessarily all, examples of the disclosure there may be provided a core network node comprising:

[0103] at least one processor;

[0104] and at least one memory storing instructions that, when executed by the at least one processor, cause the core network node at least to perform:

[0105] receiving a request for UE context relocation from an initial core network node, the request comprising at least one of:

[0106] an indication of at least one network slice configured for support of an emergency call; or

[0107] an indication to update the UE with an updated allowed list of network slices for emergency calls:

[0108] sending to the UE a message comprising an updated allowed list of network slices for emergency calls.

[0109] The request for UE context relocation may comprise a connection message associated with the UE and the processor and memory are further configured to enable the core network node to perform:

[0110] forwarding the connection message towards a session management function.

[0111] According to various, but not necessarily all, examples of the disclosure there may be provided a method comprising:

[0112] receiving a request for UE context relocation from an initial core network node, the request comprising at least one of:

[0113] an indication of at least one network slice configured for support of an emergency call; or

[0114] an indication to update the UE with an updated allowed list of network slices for emergency calls:

[0115] sending to the UE a message comprising an updated allowed list of network slices for emergency calls.

[0116] According to various, but not necessarily all, examples of the disclosure there may be provided a core network node comprising:

[0117] 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 at least to perform:

[0118] receiving a connection message associated with a UE from a network access node, the connection message comprising at least one of:

[0119] an indication of at least one network slice configured for support of an emergency call;

[0120] an indication of emergency call;

[0121] an indication to update the UE with an updated allowed list of network slices for emergency calls;

[0122] an indication to fetch a UE context from another core network node; an identification of a core network node from which the UE context is to be relocated;

[0123] based on the received connection message, fetching the UE context from the identified core network node;

[0124] sending to the UE a message comprising an updated allowed list of network slices for emergency calls for the UE.

[0125] According to various, but not necessarily all, examples of the disclosure there may be provided a method comprising:

[0126] receiving a request for UE context relocation from an initial core network node, the request comprising at least one of:

[0127] an indication of at least one network slice configured for support of an emergency call; or

[0128] an indication to update the UE with an updated allowed list of network slices for emergency calls:

[0129] sending to the UE a message comprising an updated allowed list of network slices for emergency calls.

[0130] According to various, but not necessarily all, examples of the disclosure there may be provided a user equipment (UE) comprising:

[0131] at least one processor;

[0132] and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to perform:

[0133] receiving, from a network access node, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE; determining that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE; and

[0134] sending a registration request to a core network node via a network access node to enable adding at least one of the indicated network slices into the allowed list for the UE.

[0135] The processor and memory may be configured to enable the UE to receive a response to the registration request comprising at least of the indicated network slices in the allowed list for the UE.

[0136] The indication of one or more network slices configured for support of emergency calls in the current cell may be received from the network access node in a broadcast message.

[0137] According to various, but not necessarily all, examples of the disclosure there may be provided a method comprising:

[0138] receiving, from a network access node, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE;

[0139] determining that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE; and

[0140] sending a registration request to a core network node via a network access node to enable adding at least one of the indicated network slices into the allowed list for the UE.

[0141] According to various, but not necessarily all, embodiments there is provided an apparatus comprising:

[0142] at least one processor; and

[0143] at least one memory including computer program code;

[0144] the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least a part of one or more methods described herein.

[0145] According to various, but not necessarily all, embodiments there is provided an apparatus comprising means for performing at least part of one or more methods described herein. The description of a function and / or action should additionally be considered to also disclose any means suitable for performing that function and / or action. Functions and / or actions described herein can be performed in any suitable way using any suitable method.

[0146] According to various, but not necessarily all, embodiments there is provided examples as claimed in the appended claims.

[0147] While the above examples of the disclosure and optional features are described separately, it is to be understood that their provision in all possible combinations and permutations is contained within the disclosure. It is to be understood that various examples of the disclosure can comprise any or all the features described in respect of other examples of the disclosure, and vice versa. Also, it is to be appreciated that any one or more or all the features, in any combination, may be implemented by / comprised in / performable by an apparatus, a method, and / or computer program instructions as desired, and as appropriate. The description of a function should additionally be considered to also disclose any means suitable for performing that function

[0148] BRIEF DESCRIPTION

[0149] Some examples will now be described with reference to the accompanying drawings in which:

[0150] FIG. 1 shows an example communication network;

[0151] FIGS. 2A to 2E show example methods;

[0152] FIG. 3 shows an example method;

[0153] FIG. 4 shows an example method;

[0154] FIG. 5 shows an example method;

[0155] FIG. 6 shows an example method;

[0156] FIG. 7 shows an example method;

[0157] FIG. 8 shows an example method;

[0158] FIG. 9 shows an example method; and

[0159] FIG. 10 shows an example controller.

[0160] The figures are not necessarily to scale. Certain features and views of the figures can be shown schematically or exaggerated in scale in the interest of clarity and conciseness. For example, the dimensions of some elements in the figures can be exaggerated relative to other elements to aid explication. Corresponding reference numerals are used in the figures to designate corresponding features. For clarity, all reference numerals are not necessarily displayed in all figures.

[0161] DEFINITIONS

[0162] AMF Access and Mobility Management Function

[0163] MM Mobility Management

[0164] OAM Operation, Administrations, Maintenance

[0165] PDU Packet Data Unit

[0166] RA Registration Area

[0167] RRC Radio Resource Control

[0168] S-NSSAI Single Network Slice Selection Assistance Information

[0169] TA Tracking Area

[0170] UE User Equipment

[0171] DETAILED DESCRIPTION

[0172] Fig. 1 illustrates an example of a communication network 100 to which examples of the disclosure can be applied. The communication network 100 is a cellular communication network. The communication network comprises network access nodes 102. The network access nodes 102 provide one or more cells 104. The cells 104 may define a coverage area or a service area of the corresponding network access node 102.

[0173] The network access nodes 102 can provide one or more user equipments (UE) 106 with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network access node 102 to the UE 106 and uplink (UL) communication from the UE 106 to the network access node 102. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network access nodes 102. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the UE 106.

[0174] There may be a plurality of UEs 106 in the network 100. Respective UEs 106 can be served by the same or by different network access nodes 102. If the communication network 100 comprises multiple network access nodes 102 the network access nodes 102 can be connected to each other via an interface. LTE specifications refer to such an interface as an X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes can be called an Xn interface.

[0175] The network access nodes 102 can be further connected via another interface to a core network 108 of the communication network 100. The core network 108 can comprise core network nodes. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise such as a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between terminal devices such as the UEs 106 and the core network 108. The gateway node may handle data routing in the core network 108 and to / from terminal devices such as the UEs 106. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise, for example, an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example. In other types of network other types of entities can be provided within the core network 108.

[0176] In communication networks 100 the UEs 106 can be used to make emergency calls. An emergency call is a call to an emergency service such as police, ambulance, fire brigade or any other emergency service providers. A network access node 102 can provide support for emergency calls either directly or by through fallback mechanisms towards E-UTRA or other suitable networks. The support of emergency calls by the network access node 102 can be broadcast by the network access node 102. The support of emergency calls could be broadcast in system information or any other suitable signalling.

[0177] In 5G networks, to enable emergency calls, the AMF is configured with emergency configuration data. The emergency configuration data are applied to emergency calls that are established by an AMF based on requests from the UE 106. The network slices associated with emergency calls are assumed to be configured consistently in the AMF and the network access nodes 102 within the corresponding registration area (RA) where emergency calls are to be supported.

[0178] The configuration of AMF and network access nodes 102 is done by the operation, administrations, maintenance (OAM) within the core network 108. The configuration of the emergency call support is done for respective network access nodes 102 so that different network access nodes 102 can have different configurations.

[0179] Using the AMF to configure network access nodes 102 for emergency calls assumes that there is perfect alignment of the configuration of the AMF and the network access node 102. The perfect alignment might not be realized in practice. The configuration by the OAM can be complex and does not take into account any preferences of the network access nodes 102. There may also be issues for mobility of idles UE 106. For example, if a UE 106 moves to a new tracking area or cell while in an idle mode the network access nodes 102 in the new tracking area or cell might not support the network slices that have been configured for the UE 106.

[0180] Examples of the disclosure address these issues by providing a system for configuring support for emergency calls. Examples of the disclosure could be implemented in networks as shown in Fig. 1. These could be 5G or 6G networks or any other suitable type of network.

[0181] Figs. 2A to 2E show example methods that can be performed by respective entities within a network 100 such as the network 100 shown in Fig. 1.

[0182] Fig. 2A shows an example method that could be implemented by a network access node 102.

[0183] The method comprises, at block 200, providing an indication of network slices configured for support of an emergency call. The indication is provided to at least one core network node. The core network node can be a mobility management (MM). The MM can deal with mobility management functionalities for the UE 106. An AMF is an example of an MM for a 5G network. Other types of networks can use other types of MM.

[0184] The indicated network slices can be indicated for respective cells or respective tracking areas. This can enable different network slices to be configured for support of an emergency call for different cells or tracking areas. The network access node 102 can also provide other information to the core network node. For instance the network access node 102 can provide an indication of preference associated with the indicated network slices configured for support of an emergency call. For example, the network slices could be indicated in order of preference or different levels of preference could be assigned to different network slices.

[0185] In some examples the other information that is provided to the core network node can comprise information such as network slice support of neighboring tracking areas, network slice support of neighboring cells, historical information relating to mobility statistics, emergency network slice support for neighboring tracking areas for respective core network nodes, emergency network slice support for neighboring cells for respective core network nodes, or any other information that can be used to enable the selection of network slices or improve the selection or network slices.

[0186] The indication of network slices configured for support of an emergency call can be provided in any suitable signalling. In some examples the indication of network slices configured for support of an emergency call can be provided during a setup procedure for the network access node 102 or during an update for the network access node 102.

[0187] At block 202 the method comprises receiving an emergency network slice configuration of at least one network slice. The emergency network slice configuration is received from the core network node. The at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node at block 200. That is, the selection of the network slices that are configured by the core network node takes into account the indication of network slices that was provided by the network access node.

[0188] The received emergency network slice configuration can be received for respective cells or respective tracking areas. This can enable different network slices to be configured for support of an emergency call for different cells or tracking areas.

[0189] The network access node 102 can also receive other information from the core network node. For example the network access node 102 can receive an indication of whether or not emergency calls should be enabled. In some examples the network access node 102 sends the indication of network slices configured for support of an emergency call to multiple core network nodes. In such examples the network access node 102 can receive emergency network slice configurations from multiple core network nodes. When the network access node 102 receives emergency network slice configurations from multiple core network nodes the network access node 102 can select a preferred network slice for emergency calls for respective core network nodes. That is, the network access node 102 can select different network slices that can be used for different core network nodes.

[0190] In some examples when the network access node 102 receives emergency network slice configurations from multiple core network nodes the network access node 102 can select a preferred network slice for emergency calls for respective cells or tracking areas.

[0191] The preferences for the network slices can be applied for respective UEs 106 so that different network slices for emergency calls can be preferred for different UEs 106 within the same cell or tracking area.

[0192] In some examples the method that is performed by the network access node can comprise additional blocks that are not shown in Fig. 2A. For example, the network access node 102 can be configured to broadcast information relating to the network slices for emergency calls. The broadcast information can comprise an identification of one or more network slices preferred for emergency calls in the cell, one or more network slices supported for emergency calls in the cell, one or more network slices preferred for emergency calls in the tracking area of the cell, one or more network slices supported for emergency calls in the tracking area of the cell, or any other suitable information. The broadcast information can comprise single network slice selection assistance information (S-NSSAI) or any other suitable information.

[0193] in some examples, the network access node 102 can receive a connection request from a UE 106 located in a cell. After the request has been received the network access node 102 can determine that no core network node has yet been assigned for this UE 106. The network access node 102 can then determine the preferred network slice for emergency calls for the current cell or tracking area of the UE 106 and then select a core network node to send the request to, based on at least the determined preferred network slice for emergency calls. For example, the network access node 102 can forward the request to a core network node that supports the preferred network slice for emergency calls for the current cell or tracking area of the UE 106. In other examples a core network node can be assigned for the UE 106 before the connection request is received. In such examples the network access node 102 can receive a connection request from a UE 106 located in a cell and determine the preferred network slice for emergency calls for the current cell or current tracking area comprising the cell of the UE 106. The network access node 102 can then determine the identity of the core network node which has already been assigned for this UE 106. In some cases it might also be determined that the assigned core network node does not support the determined preferred network slice for emergency calls. Based on the determining that the core network node does not support the determined preferred network slice for emergency calls the network access node 102 then, sends a message to the core network node where the message comprises relocation information. This can enable the UE 106 to be relocated to a core network node that does support the preferred network slice for emergency calls.

[0194] In some examples the network access node 102 can be arranged to determine that a received connection request from a UE 106 is for an emergency call setup. The network access node 102 can also determine that the UE 106 has an assigned core network node which does not support the preferred network slice for emergency calls for the current cell or tracking area of the UE 106. Based on this determining the network access node 102 can send a message to the core network node where the message comprises relocation information. This can enable the UE 106 to be relocated to a core network node that does support the preferred network slice for emergency calls.

[0195] The relocation information that is sent in any of the above examples can comprise a request to relocate the UE 106 to another core network node, an indication of a preferred network slice for emergency calls, an indication of a supported network slice for emergency calls, an identity of another core network node to which the UE 106 is requested to be relocated, or any other information that enables the UE 106 to be relocated.

[0196] If the network access node 102 determines that a UE that has initiated an emergency call has an assigned core network node which does not support the preferred network slice for emergency calls for the current cell or tracking area of the UE 106 then instead of sending relocation information to the currently assigned core network node the network access node 102 could sent a message to another core network node to which the UE 106 is to be relocated. In such cases the message that is sent to the another core network node can comprise a request to fetch UE context from the currently assigned core network node, an indication of a preferred network slice for emergency calls, an indication of a supported network slice for emergency calls, an identity of the assigned core network node from which the UE context is to be fetched, or any other suitable information.

[0197] In some examples the network access node 102 can be arranged to exchange information with other network access nodes 102. These can be neighboring access nodes 102. The information that is exchanged can comprise an indication of supported network slices for emergency calls for respective cells, an indication of supported network slices for emergency calls for respective tracking areas, an indication of preferred network slices for emergency calls for respective cells, an indication of preferred network slices for emergency calls for respective tracking areas, or any other suitable information. This information can be exchanged using an Xn interface. For example, the information can be exchanged in an Xn setup request or Xn setup response message. The network access node 102 can send the exchanged information from the neighboring network access nodes to the core network node.

[0198] Fig. 2B shows an example method that could be implemented by a core network node in some examples of the disclosure. The core network node can be an MM or any other suitable type of node.

[0199] The method comprises, at block 210, receiving an indication of network slices configured for support of an emergency call, from a network access node 102. This could be a network access node 102 that performs the method shown in Fig. 2A. The indication can comprise any other suitable information such as the information described above.

[0200] The indication of network slices configured for support of an emergency call can comprise an indication of network slices configured for support of an emergency call for respective cells or an indication of network slices configured for support of an emergency call for respective tracking areas.

[0201] At block 212 the method comprises configuring at least one network slice from the network access node 102 for emergency calls. The configured network slices comprise at least one of the indicated supported network slices. The network slices can be configured for respective cells or respective tracking areas In some examples the core network node receives, from the network access node 102, an indication of preference associated with the indicated slices configured for support of an emergency call. In such examples the core network node can then use the indication of preference to select the emergency network slice to be configured for emergency calls based, at least in part, on the indication of preference.

[0202] In some examples the at least one network slice that is configured for emergency call is selected based, at least in part, on the network slices supported by the core network node. A list of network slices supported by the core network node is received from an operations and maintenance system or can be provided in any other suitable manner.

[0203] At block 214 the method comprises providing the emergency network slice configuration of the at least one network slice to the network access node 102.

[0204] In some examples the core network node can be arranged to determine if emergency calls are allowed. If emergency calls are allowed then the network slice for emergency calls can be configured as at block 212. If emergency calls are not allowed then, instead of configuring a network slice for emergency calls, the core network node can provide an indication to the network access node 102 that emergency calls are not allowed. The core network node can provide an indication of whether or not emergency calls are enabled for a given cell or tracking area.

[0205] In some use case scenarios a UE 106 can relocated from one core network node to another to enable an emergency call. In such cases the core network node can receive a connection message associated with a UE 106 from a network access node 102. The connection message may be associated with the UE 106 in that it can originate from the UE 106. For example, it can be sent from the UE 106 to the network access node 102 and from the network access node 102 to the core network node. The connection message can comprise: an indication of one or more network slices configured for support of an emergency call in the cell of the UE 106, an indication of one or more network slices configured for support of an emergency call in the tracking area of the UE 106, an indication of one or more network slices preferred for support of an emergency call in the cell of the UE 106, an indication of one or more network slices preferred for support of an emergency call in the tracking area of the UE 106, a request for relocation of the UE context to another core network node, an indication of at least one other core network node onto which the UE context can be relocated or any other suitable information. The core network node can determine, based at least in part on the connection message, to relocate the UE context to another core network node and send a request for relocation of UE context the network access node or the another core network node.

[0206] Fig. 2C shows another example method that could be implemented by a core network node in some examples of the disclosure. The core network node can be an MM or any other suitable type of node. The method of Fig. 2C could be performed by a core network node to which a UE context is to be relocated. The UE context could be relocated if it is determined that the UE 106 wants to make an emergency call but the preferred network slice for emergency calls is not supported by the core network node to which the UE 106 is currently assigned.

[0207] In the example of Fig. 2C the method comprises, at block 220, receiving a request for UE context relocation from an initial core network node. The initial core network node can be the core network node to which the UE 106 is currently assigned. This could be a core network node that performs the method of Fig. 2B.

[0208] The request for UE context relocation can comprise an indication of at least one network slice configured for support of an emergency call or an indication to update the UE 106 with an updated allowed list of network slices for emergency calls.

[0209] At block 222 the method comprises sending to the UE 106 a message comprising an updated allowed list of network slices for emergency calls.

[0210] In some examples the request for UE context relocation can comprises a connection message associated with the UE 106. The core network node can forward the connection message towards a session management function.

[0211] Fig. 2D shows another example method that could be implemented by a core network node in some examples of the disclosure. The core network node can be an MM or any other suitable type of node. The method of Fig. 2D could be performed by a core network node to which a UE context is to be relocated. The UE context could be relocated if it is determined that the UE 106 wants to make an emergency call but the preferred network slice for emergency calls is not supported by the core network node to which the UE 106 is currently assigned. In this example, the core network node to which the UE 106 is to be relocated fetches the UE context from the initial core network node. In the example of Fig. 2D the method comprises, at block 230, receiving a request for connection message from a network access node 102. The connection message can comprise an indication of at least one network slice configured for support of an emergency call, an indication of emergency call, an indication to update the UE 106 with an updated allowed list of network slices for emergency calls, an indication to fetch a UE context from another core network node, an identification of a core network node from which the UE context is to be relocated, or any other suitable information.

[0212] At block 232 the core network node fetches the UE context from the identified core network node. The fetching of the UE context is performed based on the information received in the connection message.

[0213] At block 234 the method comprises sending to the UE 106 a message comprising an updated allowed list of network slices for emergency calls for the UE 106.

[0214] Fig. 2E shows another example method that could be implemented by a UE 106 in some examples of the disclosure. The UE 106 can be connected to a network access node 102 that performs the method of Fig. 2A, or to any other suitable network entities.

[0215] The method comprises, at block 240, receiving, from a network access node 102, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE 106. The indication of one or more network slices configured for support of emergency calls in the current cell can be received from the network access node 102 in a broadcast message.

[0216] At block 242 the method comprises, determining that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE 106.

[0217] At block 244 the method comprises, sending a registration request to a core network node via a network access node 102 to enable adding at least one of the indicated network slices into the allowed list for the UE 106. In response to the registration request the UE 106 can receive the indicated network slices in the allowed list for the UE.

[0218] Fig. 3 shows an example method that can be used in examples of the disclosure. The method of Fig. 3 shows a network access node 102 obtaining information that enables support of emergency calls. The information can comprise an emergency network slice configuration and / or any other suitable information. At block 300 the core network node is configured with emergency configuration data. In this case the core network node is an MM 314. Other types of core nodes could be used in examples of the disclosure. The MM 314 can be configured by another entity within the core network 108 such as an OAM, or any other suitable entity. For example, the OAM can provide emergency configuration data to the MM 314.

[0219] The emergency configuration data can comprise a list of network slices that can be used to support emergency calls by the MM 314. In some examples the emergency configuration data can comprise identifiers to be used for the respective network slices. The identifiers can comprise S-NSSAIs or any other suitable identifiers.

[0220] The network slices that can be used to support emergency calls can be configured for respective cells or tracking areas.

[0221] At block 302 the network access node 102 sends a setup request to the MM 314. The setup request can be part of a set up procedure. The setup procedure enables the setup of an interface between the network access node 102 and the MM 314.

[0222] The setup request that is sent by the network access node 102 comprises an indication of network slices configured for support of an emergency call. The network slices configured for support of an emergency call can be indicated for respective cells or respective TAs.

[0223] The set up request also comprises an indication of preference for respective network slices configured for support of an emergency call. For example, the network slices can be provided in an ordered list or can be marked with a level of preference. The indication of preference can be used by the MM 314 when determining the emergency slice configuration for TAs or cells.

[0224] The indication of network slices configured for support of an emergency call can be sent from the network access node 102 to the MM 314 using other types of signalling in other examples. For instance, instead of the setup request the indication of network slices configured for support of an emergency call could be provided in a configuration update procedure. This could be used to change the supported network slices or to change the preferences of the supported network slices. If a service based interface (SBI) is used between the network access node 102 and the MM 314 then the indication of network slices configured for support of an emergency call and the preference for the respective slices can be obtained from the profile of the network access node 102. This information could be obtained via network function repository function (NRF) or any other suitable means.

[0225] In some examples the network access node 102 can also provide other information to the MM 314. For example the network access node 102 can provide an indication of whether emergency calls are allowed or not allowed for respective cells or TAs.

[0226] Other information that could be comprised in the setup request 302, or other suitable signalling to the MM 314, can comprise, network slice support of neighboring cells or TAs, historical information relating to statistics, emergency network slice support for respective MMs 314 and neighboring cells or TAs. This information can be obtained from other network access nodes 102. The information can be obtained via an Xn interface or any other suitable interface.

[0227] In some examples, instead of the network access node 102 providing information about neighboring cells or TAs to the MM 314 the network access node 102 could provide only an indication of the neighboring network access nodes and the MM 314 can use this information to determine the network slice support and emergency network slice support for neighboring cells or TAs.

[0228] At block 304 the MM 314 determine if an emergency call is allowed for respective cells or TAs. The MM 314 can use the information provided by the network access node 102 to determine if an emergency call is allowed for a respective cells or TAs.

[0229] If emergency calls are allowed then the method proceeds to block 306 and the MM 314 configures at least one network slice for emergency calls. If emergency calls are not allowed then the method terminates at block 304 and no network slices are selected to support emergency calls. If emergency calls are not allowed then fallback procedures could be used to facilitate emergency calls.

[0230] At block 306 the MM 314 selects one or more network slices to be used for emergency calls. The network slices that are selected can comprise one or more of the network slices that were configured for the MM 314 at block 300. The MM 314 can use the information provided from the network access node 102, such as the preference of the network slices, in order to select the one or more network slices to be used for emergency calls.

[0231] If the MM 314 does not find any suitable network slices for a cell or TA then, at block 308, the MM 314 determines that emergency calls are not allowed for that cell or TA. If emergency calls are not allowed then fallback procedures could be used to facilitate emergency calls.

[0232] At block 310 the MM 314 sends a setup response to the network access node 102. The setup response can comprise the emergency network slice configuration of at least one network slice. The network slice is a slice that the MM 314 has selected from the list of supported network slices that were indicated in the setup request. The emergency network slice configuration can be indicated for respective cells or TAs. The set up response can comprise identifiers of the respective network slices such as S-NSSAIs or any other suitable information.

[0233] In some examples the setup response that is sent to the network access node 102 can comprise other information. For example, the setup response could comprise an indication of whether emergency calls are allowed or not allowed for a given cell or TA.

[0234] At block 312 the network access node 102 broadcasts support of emergency calls. This can enable emergency calls using the selected network slice that has been configured for emergency calls. The broadcast emergency support can comprise a list of the network slices for which emergency calls are supported. The network slices can be indicated for respective cells or TAs so that different network slices can be used for different cells or TAs. The broadcast can comprise identifiers of the respective network slices such as S-NSSAIs or any other suitable information.

[0235] It is possible for a network access node 102 to connect to more than one MM 314. Provided that at least one MM 314 has configured the network node with an emergency network slice then the network access node 102 can broadcast support of emergency calls.

[0236] In the example of Fig. 3 the network access node 102 provides the indication of the supported network slices for an emergency call in the setup request. This indication could be provided in other signalling, such as configuration update procedures. The configuration update procedures, or other suitable signalling can also enable updates or changes to be made to the list of supported network slices and the corresponding preferences. However, the indication of the supported network slices for an emergency call is received the MM 314 can use the indication to configure at least one network slice for emergency calls.

[0237] Once the method of Fig. 3 has been completed the MM 314 can support emergency calls that are initiated by the UE 106 for a given cell or TA.

[0238] Fig. 4 shows another example method that can be used in examples of the disclosure. In this example the network access node 102 is connected to multiple MMs 314. In the example of Fig. 4 two MMs 314 are shown but the network access node 102 could be connected to any number of MMs 314.

[0239] In the example of Fig. 4 the network access node 102 can select a preferred MM 314 for supporting emergency calls for the UE 106.

[0240] The MMs 314 can be configured to support different network slices. As an illustrative example, the first MM 314 in Fig. 4 could be configured to support network slices S-NSSAI 1 , S-NSSAI 2, and S-NSSAI 3 and the second MM 314 could be configured to support network slices S-NSSAI 3, S-NSSAI 4, and S-NSSAI 5.

[0241] The network access node 102 can send an indication of network slices configured for support of an emergency call and an indication of preference for respective network slices to each of the multiple MMs 314. In the example of Fig. 4 this could be sent in a setup request. The setup request could be as shown in Fig. 3. Other types of signalling could be used in other examples.

[0242] The respective MMs 314 can configure one or more network slices for the network access node 102 for supporting emergency calls. The configuration of the one or more network slices for the network access node 102 for supporting emergency calls is based on the indication of network slices configured for support of an emergency call and the indication of preference for respective network slices that is received from the network access node 102. As the MMs 314 support different network slices, the respective MMs 314 can select different network slices for supporting emergency calls.

[0243] If the emergency calls are allowed by multiple MMs 314 then the method of Fig. 4 can be used. At block 400 the network access node 102 receives a first setup response from a first MM 314 and at block 402 the network access node 102 receives a second setup response from a second MM 314. These setup responses can be as shown in Fig. 3 and described above. They can be sent following a setup request from the network access node 102 and selection of one or more network slices or following any other suitable signalling.

[0244] The respective setup responses comprise the emergency network slice configuration of at least one network slice. These can be different network slices for the different MMs 314. For instance the first set up response 400 from the first MM 314 can comprise the emergency network slice configuration of S-NSSAI 1 and the second set up response 402 from the second MM 314 can comprise the emergency network slice configuration of S-NSSAI 4. In this case each of the network slice configurations are for the same cell or tracking area.

[0245] At block 404 the network access node 102 broadcasts support of emergency calls. This can enable emergency calls using the selected network slice that has been configured for emergency calls. The broadcast can comprise identifiers of the respective network slices such as S-NSSAIs or any other suitable information. In this case the network node can broadcast that S-NSSAI 1 and S-NSSAI 4 are the emergency network slices for a particular cell or TA.

[0246] At block 406 the network access node 102 receives a connection setup from the UE 106. The connection setup can comprise a radio resource control (RRC) connection setup or any other suitable signalling. In this example there is no MM 314 assigned in the connection setup from the UE 106.

[0247] At block 408 the network access node 102 selects an MM 314. The MM 314 can be selected based on the preference of the network nodes 102 or any other suitable criteria. The selection of the MM 314 can take into account factors such as load characteristics, network conditions, or any other suitable factors.

[0248] The selection of the MM 314 can be performed by the non-access stratum (NAS) node selection function (NNSF) of the network access node 102, or by any other suitable entity.

[0249] In this case the network access node 102 can select the second MM 314 because the network node can have a preference for network slice S-NSSAI 4 and network slice S- NSSAI 4 is supported by the second MM 314. The network access node 102 can select different MMs 314 for different UE 106. For example, the network node could have different preferences for different UEs 106 which leads to different MMs 314 being selected. For example some UEs 106, such as UEs 106 that provide public safety, could be provided with a higher priority and different preferences to other UEs 106.

[0250] Following the selection of the second MM 314, at block 410, the network access node 102 forwards the initial UE message to the second MM 314. The second MM 314 can then, at block 412 send a register accept signal. The register accept signal is sent to the UE 106 via the network access node 102. The register accept signal can comprise the emergency network slice configuration of the network slice that is to be used for emergency calls. The information that is provided to the UE 106 can comprise the S-NSSAI of the network slice and / or any other suitable information.

[0251] Once the method of Fig. 4 has been completed the second MM 314 can support emergence calls that are initiated by the UE 106 for a given cell or TA.

[0252] Fig. 5 shows an example method that can be used if the UE 106 moves to a new cell or tracking area that does not support the configured emergency network slice for the cell or TA in which the UE 106 resides. In such cases the UE 106 can trigger re-registration and the MM 314 can perform MM relocation to a different MM 314 that does support the configured emergency network slice for the cell orTA in which the UE 106 is now located. If the UE 106 initiates an emergency call after the MM relocation has been performed then this can be managed by the MM 314 to which the UE 106 has been relocated.

[0253] The method shown in Fig. 5 could be performed after an emergency network slice has been configured. The emergency network slice could be configured using the methods of Figs. 3 and / or 4, and / or any other suitable methods.

[0254] In the example of Fig. 5 the MMs 314 can be configured to support different network slices as shown in Fig. 4. In this case the first MM 314 could be configured to support network slices S-NSSAI 1 , S-NSSAI 2, and S-NSSAI 3 and the second MM 314 could be configured to support network slices S-NSSAI 3, S-NSSAI 4, and S-NSSAI 5. In this illustrative example the second MM 314 has been selected by the network access node 102 to support emergency calls for the UE 106. At block 500 the UE 106 is in an idle mode. The second MM 314 has been selected by the network access node 102 to support emergency calls for the UE 106. The network slice S-NSSAI 4 is configured for supporting emergency calls for the UE 106 in the cell or TA in which the UE 106 is currently located. The allowed emergency network slice can be indicated in an allowed list for the UE 106.

[0255] At block 502 the UE 106 moves to a new cell or TA. The UE 106 can move to the new cell or TA while it is in idle mode. This new cell or TA does not support the network slice S-NSSAI 4 for emergency calls. In some examples the network slice configured for emergency calls could be supported in the new cell or TA but a different network slice could be preferred.

[0256] At block 504 the network access node 102 broadcasts emergency support. The broadcast emergency support can comprise a list of the network slices for which emergency calls are supported. The network slices can be indicated for respective cells or TAs so that different network slices can be used for different cells or TAs. The broadcast can comprise identifiers of the respective network slices such as S-NSSAIs or any other suitable information.

[0257] In this example the broadcast emergency support indicates that network slice S-NSSAI 1 is configured for supporting emergency calls in the new cell or TA that the UE 106 has moved into.

[0258] The network access node 102 can broadcast emergency support at predefined times or in response to any suitable trigger events. In some examples the network access node 102 can broadcast emergency support periodically.

[0259] At block 506 the UE 106 triggers re-registration. The re-registration can be triggered based on the information in the broadcast emergency support. The UE 106 can compare the network slice that has been configured for supporting emergency calls for the UE 106 and the list of network slices for which emergency calls are supported that is broadcast by the network access node 102. The UE 106 can determine that the network slice that has been configured for supporting emergency calls for the UE 106 is not in the list of network slices for which emergency calls are supported that is broadcast by the network access node 102. Therefore the UE 106 can determine that it is now in a cell or TA in which the network slice that has been configured for supporting emergency calls for the UE 106 is not supported. For instance, in this example, the network slice S- NSSAI 4 is initially configured for supporting emergency calls for the UE 106 but network slice S-NSSAI 4 is not supported by the network access node 102 for the new cell or TA. Instead the network access node 102 will broadcast that it can support network slices S-NSSAI 1 , S-NSSAI 2, and S-NSSAI 3.

[0260] The UE 106 can trigger the re-registration at any suitable time. In some examples the reregistration could be triggered when an emergency call is initiated. For instance, when an emergency call is initiated the UE 106 can then check the network slices that are supported for emergency calls. In other examples the UE 106 could check the network slices that are supported for emergency calls at other times, such as when the broadcast emergency support is received.

[0261] At block 508 the UE 106 sends the re-registration request to the second MM 314. The re-registration request is sent to the second MM 314 because the second MM 314 has been selected by the network access node 102 to support emergency calls for the UE 106.

[0262] At block 510 the second MM 314 receives the re-registration request and determines to relocate the UE 106 to the first MM 314. When the second MM 314 receives the reregistration request it determines, based on the received cell ID and / or any other suitable information, that the UE 106 is now in a cell or TA for which the second MM 314 does not support the emergency network slice. The second MM 314 therefore determines to relocate the UE 106 to the first MM 314 which supports the emergency network slice for the cell or TA in which the UE 106 is now located.

[0263] At block 512 the second MM 314 relocates the UE 106 to the first MM 314. For example the UE context can be sent from the second MM 314 to the first MM 314. The request for context relocation can comprise an indication of network slices configured for support for an emergency call or an indication that a UE 106 is to be updated with a new or updated allowed list of network slices for emergency calls.

[0264] At block 514 a register accept update is sent from the first MM 314 to the UE 106. The register accept update signal can comprise the emergency network slice configuration of the network slice that is to be used for emergency calls. The information that is provided to the UE 106 can comprise the S-NSSAI of the network slice and / or any other suitable information. In this case the register accept update would indicate that S-NSSAI 1 is supported for emergency calls. At block 516 the UE 106 can initiate an emergency call. This can occur some time after the UE 106 receives the register accept update. Packet data unit (PDU) session establishment is performed with the first MM 314 to establish the emergency call.

[0265] Therefore examples of the disclosure enable the UE 106 to be relocated to a different MM 314 to support emergency calls if the UE 106 moves into a new cell or TA while in an idle mode.

[0266] Fig. 6 shows another example method that can be used in examples of the disclosure. The method of Fig. 6 shows a network access node 102 obtaining information that enables support of emergency calls. The information can comprise an emergency network slice configuration and / or any other suitable information.

[0267] Blocks 300 to 310 of Fig. 6 can be as shown in Fig. 3 and corresponding reference numerals are used for the respective blocks of the method.

[0268] The method of Fig. 6 differs from the method of Fig. 3 in that, at block 600, the network access node 102 broadcasts support of emergency calls. This information in this example, doesn’t include the specific slices that are supported. For example, the S-NSSAI information, or other similar information that was included in the example of Fig.

[0269] 3 is not included here.

[0270] Fig. 7 shows another example method that can be used in examples of the disclosure. In this example the network access node 102 is connected to multiple MMs 314. In the example of Fig. 7 two MMs 314 are shown but the network access node 102 could be connected to any number of MMs 314.

[0271] Blocks 400 and 402 of Fig. 7 can be as shown in Fig. 4 and corresponding reference numerals are used for the respective blocks of the method.

[0272] The method of Fig. 7 differs from the method of Fig. 4 in that, at block 700, the network access node 102 broadcasts support of emergency calls. This information in this example, doesn’t include the specific slices that are supported. For example, the S-NSSAI information, or other similar information that was included in the example of Fig.

[0273] 4 is not included here. Similarly blocks 406 to 410 can be as shown in Fig. 4 and corresponding reference numerals are used for the respective blocks of the method. However at block 702 The second MM 314 can then, at block 412 send a register accept signal. The register accept signal is sent to the UE 106 via the network access node 102. The register accept signal in this example doesn’t include the specific slices that are supported. For example, the S-NSSAI information, or other similar information that was included in the example of Fig. 4 is not included here.

[0274] Fig. 8 shows an example method that can be used if the UE 106 has moved to a new cell or tracking area that does not support the configured emergency network slice for the cell or TA in which the UE 106 resides. This can be used in cases, such as those shown in Figs. 6 and 7, where the UE 106 does not receive information about the specific slices such as the S-NSSAI information from for the emergency network slices.

[0275] In the example of Fig. 8 the network access node 102 can trigger relocation of the UE 106 to a different MM 314 that does support the configured emergency network slice for the cell or TA to which the UE 106 has moved. If the UE 106 initiates an emergency call after the MM relocation has been performed then this can be managed by the MM 314 to which the UE 106 has been relocated.

[0276] The method shown in Fig. 8 could be performed after emergency network slice has been configured. The emergency network slice could be configured using the methods of Figs.

[0277] 6 and / or 7, and / or any other suitable methods.

[0278] In the example of Fig. 8 the MMs 314 can be configured to support different network slices as shown in Fig. 7. In this case the first MM 314_1 could be configured to support network slices S-NSSAI 1 , S-NSSAI 2, and S-NSSAI 3 and the second MM 314_2 could be configured to support network slices S-NSSAI 3, S-NSSAI 4, and S-NSSAI 5. In this illustrative example the second MM 314_2 has been selected by the network access node 102 to support emergency calls for the UE 106.

[0279] At block 800 the UE 106 is in an idle mode. The second MM 314_2 has been selected by the network access node 102 to support emergency calls for the UE 106. The network slice S-NSSAI 4 is configured for supporting emergency calls for the UE 106 in the cell or TA in which the UE 106 is currently located. The allowed emergency network slice can be indicated in an allowed list for the UE 106. At block 802 the UE 106 moves to a new cell or TA. The UE 106 can move to the new cell or TA while it is in idle mode. This new cell or TA does not support the network slice S-NSSAI 4 for emergency calls. In some examples the network slice configured for emergency calls could be supported in the new cell or TA but a different network slice could be preferred.

[0280] At block 804 the network access node 102 broadcasts emergency support. The broadcast emergency support can comprise a list of the network slices for which emergency calls are supported. The network slices can be indicated for respective cells or TAs so that different network slices can be used for different cells or TAs. In this example the broadcast does not comprise identifiers of the respective network slices such as S-NSSAIs or any other similar information.

[0281] At block 806 the UE 106 starts an emergency call. However the emergency network slice for the current cell or TA of the UE 106 is not on the allowed list for the UE 106. In this case S-NSSAI 1 is the emergency network slice for the current cell or TA of the UE 106 but this is not supported by the second MM 314.

[0282] At block 808 the network access node 102 receives a connection setup from the UE 106. The connection setup can comprise a radio resource control (RRC) connection setup or any other suitable signalling. The connection setup can be for establishing the emergency call. The connection set up can be for PDU session establishment. The second MM 314_2 can be assigned in the connection setup. However the connection setup is from a cell or TA that does not support an emergency call on a network slice that is configured for the second MM 314_2.

[0283] At block 810 the network access node 102 determines that the emergency call is started from a cell for which the assigned MM 314_2 does not support an emergency call. The network access node 102 can determine that the UE 106 has sent the connection setup from a cell or TA that does not support an emergency call on a network slice that is configured for the second MM 314_2. The network access node 102 can make this determination based on the service cell or TA for the UE 106.

[0284] At block 812, the network access node 102 forwards the PDU session establishment request to the second MM 314_2. The network access node 102 can request a relocation of the MM 314. The network access node 102 can indicate a preferred target MM 314, for example it could indicate that the UE 106 is relocated to the first MM 314_1. The preferred MM 314 can be selected based on the cell of the UE 106 and the network slices that are supported by the respective MMs 314. The network access node 102 can also request an update of the allowed list of network slices.

[0285] At block 814 the second MM 314_2 sends a relocation request to the first MM 314_1. The second MM 314_2 can also send a request to perform a UE context transfer update. This can request that the UE context is transferred from the second MM 314_2 to the first MM 314_1. The relocation request can include an updated list of allowed network slices for emergency calls. The relocation request can include an indication to provide the updated list of allowed network slices for emergency calls to the UE 106.

[0286] At block 816 a configuration update is sent from the first MM 314_1 to the UE 106. The configuration update can comprise an updated allowed network slice list for emergency calls for the UE 106. The configuration update can comprise the S-NSSAI 1 which is configured for emergency calls in the current cell or TA of the UE 106.

[0287] At block 818 the first MM 314_1 forwards the PDU Session Establishment request, or other connection setup request to session management (SM) function 822 for emergency calls in S-NSSAI 1.

[0288] At block 820 the UE 106 initiates PDU session establishment in the new allowed network slice with the first MM 314_1 for an emergency call.

[0289] Fig. 9 shows another example method that can be used if the UE 106 has moved to a new cell or tracking area that does not support the configured emergency network slice for the cell or TA in which the UE 106 resides. This can be used in cases, such as those shown in Figs. 6 and 7, where the UE 106 does not receive information about the specific slices such as the S-NSSAI information from for the emergency network slices.

[0290] This example is similar to the example of Fig. 8 except that the network access node 102 determines that the UE 106 should be relocated to a different MM 314 and send the request for the relocation to the current MM 314.

[0291] Blocks 800 to 808 of Fig. 9 can be as shown in Fig. 8 and corresponding reference numerals are used for the respective blocks of the method. At block 900 the network access node 106 determines that the emergency call is started from a cell for which the assigned MM 314_2 does not support an emergency call. The network access node 102 can determine that the UE 106 has sent the connection setup from a cell or TA that does not support an emergency call on a network slice that is configured for the second MM 314_2. The network access node 102 can make this determination based on the service cell or TA for the UE 106.

[0292] At block 902 the network access node 102 sends a connection message associated with the UE 106 to the first MM 314_1. For example, the network access node 102 can forward the PDU session establishment request to the first MM 314_1. The first MM 314_1 is the MM 314 to which the UE context is to be relocated.

[0293] The connection message that is sent to the first MM 314_1 can comprise an indication of at least one network slice configured for support of an emergency call, an indication of emergency call, an indication to update the UE 106 with an updated allowed list of network slices for emergency calls, an indication to fetch a UE context from the second MM 314_2, an identification of the second MM 314_2 from which the UE context is to be relocated, and / or any other suitable information.

[0294] At block 904 the first MM 314_1 fetches the UE context from the second MM 314_2 and MM relocation is performed.

[0295] At block 906 a configuration update is sent from the first MM 314_1 to the UE 106. The configuration update can comprise an updated allowed network slice list for emergency calls for the UE 106.

[0296] At block 908 the first MM 314_1 forwards the PDU Session Establishment request, or other connection setup request to SM function 822 for emergency calls in S-NSSAI 1 .

[0297] At block 910 the UE 106 initiates PDU session establishment in the new allowed network slice with the first MM 314_1 for an emergency call.

[0298] Fig. 10 shows an example controller 1000. The controller 1000 could be provided within a UE 106, a network access node 102, a core network node any other suitable entity. Implementation of the controller 1000 may be as controller circuitry. The controller 1000 may be implemented in hardware alone, have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware). The controller 1000 can be used to control a device comprising multiple radio subsystems or could be used to control one or more of the radio subsystems within a device. The controller 1000 can provide an apparatus for implementing the disclosure of could be provided as part of an apparatus that implements the disclosure.

[0299] As illustrated in Fig. 10 the controller 1000 can be implemented using instructions that enable hardware functionality, for example, by using executable instructions of a computer program 1006 in a general-purpose or special-purpose processor 1002 that may be stored on a computer readable storage medium (disk, memory etc.) to be executed by such a processor 1002.

[0300] The processor 1002 is configured to read from and write to the memory 1004. The processor 1002 may also comprise an output interface via which data and / or commands are output by the processor 1002 and an input interface via which data and / or commands are input to the processor 1002.

[0301] The memory 1004 stores a computer program 1006 comprising computer program instructions (computer program code) that controls the operation of the apparatus when loaded into the processor 1002. The computer program instructions, of the computer program 1006, provide the logic and routines that enables the apparatus to perform the methods illustrated in the Figs. The processor 1002 by reading the memory 1004 is able to load and execute the computer program 1006.

[0302] In some examples where the controller 1000 is provided within an apparatus that controls a network access node 102, the controller 1000 therefore comprises means for:

[0303] providing 200 an indication of network slices configured for support of an emergency call, to at least one core network node; and

[0304] receiving 202 an emergency network slice configuration of at least one network slice from the at least one core network node where the at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

[0305] In some examples where the controller 1000 is provided within an apparatus that controls a core network node , the controller 1000 therefore comprises means for:

[0306] receiving 210 an indication of network slices configured for support of an emergency call, from a network access node 102; configuring 212 at least one network slice from the network access node 102 for emergency calls wherein the configured network slices comprise at least one of the indicated supported network slices; and

[0307] providing 214 the emergency network slice configuration of the at least one network slice to the network access node 102.

[0308] In some examples where the controller 1000 is provided within an apparatus that controls a core network node, the controller 1000 therefore comprises means for:

[0309] receiving 220 a request for UE context relocation from an initial core network node, the request comprising at least one of:

[0310] an indication of at least one network slice configured for support of an emergency call; or

[0311] an indication to update the UE with an updated allowed list of network slices for emergency calls:

[0312] sending 222 to the UE 106 a message comprising an updated allowed list of network slices for emergency calls.

[0313] In some examples where the controller 1000 is provided within an apparatus that controls a core network node, the controller 1000 therefore comprises means for:

[0314] receiving 230 a connection message associated with a UE from a network access node 102, the connection message comprising at least one of:

[0315] an indication of at least one network slice configured for support of an emergency call;

[0316] an indication of emergency call;

[0317] an indication to update the UE with an updated allowed list of network slices for emergency calls;

[0318] an indication to fetch a UE context from another core network node; an identification of a core network node from which the UE context is to be relocated;

[0319] based on the received connection message, fetching 232 the UE context from the identified core network node;

[0320] sending 234 to the UE 106 a message comprising an updated allowed list of network slices for emergency calls for the UE 106.

[0321] In some examples where the controller 1000 is provided within an apparatus that controls a first radio subsystem, the controller therefore comprises means for: receiving 240, from a network access node 102, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE 106;

[0322] determining 242 that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE 106; and

[0323] sending 244 a registration request to a core network node via a network access node 102 to enable adding at least one of the indicated network slices into the allowed list for the UE 106.

[0324] The computer program 1006 may arrive at the apparatus via any suitable delivery mechanism 1008. The delivery mechanism 1008 may be, for example, a machine-readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a Compact Disc Read-Only Memory (CD-ROM) or a Digital Versatile Disc (DVD) or a solid-state memory, an article of manufacture that comprises or tangibly embodies the computer program 1006. The delivery mechanism may be a signal configured to reliably transfer the computer program 1006. The apparatus may propagate or transmit the computer program 1006 as a computer data signal.

[0325] The computer program 1006 can comprise computer program instructions for causing a network access node 102 to perform at least the following or for performing at least the following:

[0326] providing 200 an indication of network slices configured for support of an emergency call, to at least one core network node; and

[0327] receiving 202 an emergency network slice configuration of at least one network slice from the at least one core network node where the at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

[0328] The computer program 1006 can comprise computer program instructions for causing a core network node to perform at least the following or for performing at least the following:

[0329] receiving 210 an indication of network slices configured for support of an emergency call, from a network access node 102;

[0330] configuring 212 at least one network slice from the network access node 102 for emergency calls wherein the configured network slices comprise at least one of the indicated supported network slices; and providing 214 the emergency network slice configuration of the at least one network slice to the network access node 102.

[0331] The computer program 1006 can comprise computer program instructions for causing a core network node to perform at least the following or for performing at least the following: receiving 220 a request for UE context relocation from an initial core network node, the request comprising at least one of:

[0332] an indication of at least one network slice configured for support of an emergency call; or

[0333] an indication to update the UE with an updated allowed list of network slices for emergency calls:

[0334] sending 222 to the UE 106 a message comprising an updated allowed list of network slices for emergency calls.

[0335] The computer program 1006 can comprise computer program instructions for causing a core network node to perform at least the following or for performing at least the following:

[0336] receiving 230 a connection message associated with a UE from a network access node 102, the connection message comprising at least one of:

[0337] an indication of at least one network slice configured for support of an emergency call;

[0338] an indication of emergency call;

[0339] an indication to update the UE with an updated allowed list of network slices for emergency calls;

[0340] an indication to fetch a UE context from another core network node; an identification of a core network node from which the UE context is to be relocated;

[0341] based on the received connection message, fetching 232 the UE context from the identified core network node;

[0342] sending 234 to the UE 106 a message comprising an updated allowed list of network slices for emergency calls for the UE 106.

[0343] The computer program 1006 can comprise computer program instructions for causing a UE 106 to perform at least the following or for performing at least the following:

[0344] receiving 240, from a network access node 102, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE 106; determining 242 that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE 106; and

[0345] sending 244 a registration request to a core network node via a network access node 102 to enable adding at least one of the indicated network slices into the allowed list for the UE 106.

[0346] The computer program instructions may be comprised in a computer program, a non-transitory computer readable medium, a computer program product, a machine-readable medium. In some but not necessarily all examples, the computer program instructions may be distributed over more than one computer program.

[0347] Although the memory 1004 is illustrated as a single component / circuitry it may be implemented as one or more separate components / circuitry some or all of which may be integrated / removable and / or may provide permanent / semi-permanent / dynamic / cached storage.

[0348] Although the processor 1002 is illustrated as a single component / circuitry it may be implemented as one or more separate components / circuitry some or all of which may be integrated / removable. The processor 1002 may be a single core or multi-core processor.

[0349] References to “computer-readable storage medium”, “computer program product”, “tangibly embodied computer program” etc. or a “controller”, “computer”, “processor” etc. should be understood to encompass not only computers having different architectures such as single / multi- processor architectures and sequential (Von Neumann) / parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

[0350] As used in this application, the term “circuitry” can refer to one or more or all of the following:

[0351] (a) hardware-only circuitry implementations (such as implementations in only analog and / or digital circuitry) and

[0352] (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

[0353] (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 (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 might not be present when it is not needed for operation.

[0354] 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 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 for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0355] The blocks illustrated in the Figs, can represent steps in a method and / or sections of code in the computer program 1006. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block can be varied. Furthermore, it can be possible for some blocks to be omitted.

[0356] The above-described examples find application as enabling components of: automotive systems; telecommunication systems; electronic systems including consumer electronic products; distributed computing systems; media systems for generating or rendering media content including audio, visual and audio visual content and mixed, mediated, virtual and / or augmented reality; personal systems including personal health systems or personal fitness systems; navigation systems; user interfaces also known as human machine interfaces; networks including cellular, non-cellular, and optical networks; ad-hoc networks; the internet; the internet of things; virtualized networks; and related software and services.

[0357] The apparatus can be provided in an electronic device, for example, a mobile terminal, according to an example of the present disclosure. It should be understood, however, that a mobile terminal is merely illustrative of an electronic device that would benefit from examples of implementations of the present disclosure and, therefore, should not be taken to limit the scope of the present disclosure to the same. While in certain implementation examples, the apparatus can be provided in a mobile terminal, other types of electronic devices, such as, but not limited to: mobile communication devices, hand portable electronic devices, wearable computing devices, portable digital assistants (PDAs), pagers, mobile computers, desktop computers, televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices and other types of electronic systems, can readily employ examples of the present disclosure. Furthermore, devices can readily employ examples of the present disclosure regardless of their intent to provide mobility.

[0358] The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to ‘comprising only one...’ or by using ‘consisting.’

[0359] In this description, the wording ‘connect’, ‘couple’ and ‘communication’ and their derivatives mean operationally connected / coupled / in communication. It should be appreciated that any number or combination of intervening components can exist (including no intervening components), i.e., to provide direct or indirect connection / coupling / communication. Any such intervening components can include hardware and / or software components.

[0360] As used herein, the term "determine / determining" (and grammatical variants thereof) can include, not least: calculating, computing, processing, deriving, measuring, investigating, identifying, looking up (for example, looking up in a table, a database, or another data structure), ascertaining and the like. Also, "determining" can include receiving (for example, receiving information), accessing (for example, accessing data in a memory), obtaining and the like. Also, " determine / determining" can include resolving, selecting, choosing, establishing, and the like.

[0361] In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’, or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example.

[0362] 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 the elements.

[0363] Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

[0364] Features described in the preceding description may be used in combinations other than the combinations explicitly described above.

[0365] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0366] The description of a feature, such as an apparatus or a component of an apparatus, configured to perform a function, or for performing a function, should additionally be considered to also disclose a method of performing that function. For example, description of an apparatus configured to perform one or more actions, or for performing one or more actions, should additionally be considered to disclose a method of performing those one or more actions with or without the apparatus.

[0367] Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not.

[0368] The term ‘a’, ‘an’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a / an / the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’, ‘an’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning.

[0369] The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result.

[0370] In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described.

[0371] The above description describes some examples of the present disclosure however those of ordinary skill in the art will be aware of possible alternative structures and method features which offer equivalent functionality to the specific examples of such structures and features described herein above and which for the sake of brevity and clarity have been omitted from the above description. Nonetheless, the above description should be read as implicitly including reference to such alternative structures and method features which provide equivalent functionality unless such alternative structures or method features are explicitly excluded in the above description of the examples of the present disclosure.

[0372] Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not emphasis has been placed thereon.

[0373] l / we claim:

Claims

43CLAIMS1. A network access node comprising:at least one processor;and at least one memory storing instructions that, when executed by the at least one processor, cause the network node at least to perform:providing an indication of network slices configured for support of an emergency call, to at least one core network node; andreceiving an emergency network slice configuration of at least one network slice from the at least one core network node where the at least one configured emergency network slice comprises at least one of the network slices indicated by the network access node.

2. The network access node of claim 1 wherein the processor and memory are further configured to perform:providing, to the core network node, an indication of preference associated with the indicated network slices configured for support of an emergency call.

3. The network access node of claims 1 and 2 wherein the indicated network slices are indicated for at least one of:respective cells;respective tracking areas.

4. The network access node of claims 1 to 3 wherein the received emergency network slice configuration is received for at least one of:respective cells;respective tracking areas.

5. The network access node of any of claims 1 to 4 wherein the indication of network slices configured for support of an emergency call comprises one or more of:network slice support of neighboring tracking areas;network slice support of neighboring cells;historical information relating to mobility statistics;emergency network slice support for neighboring tracking areas for respective core network nodes;44emergency network slice support for neighboring cells for respective core network nodes.

6. The network access node of any preceding claim wherein the processor and memory are further configured to perform:receiving an emergency network slice configuration from multiple core network nodes; andselecting a preferred network slice for emergency calls for respective core network nodes.

7. The network access node of any preceding claim wherein the processor and memory are further configured to perform:receiving an emergency network slice configuration from multiple core network nodes; andselecting a preferred network slice for emergency call to be used for at least one of:respective cells;respective tracking areas.

8. The network access node of any preceding claim wherein the processor and memory are further configured to perform:broadcasting in a cell at least one of:one or more network slices preferred for emergency calls in the cell;one or more network slices supported for emergency calls in the cell;one or more network slices preferred for emergency calls in the tracking area of the cell;one or more network slices supported for emergency calls in the tracking area of the cell.

9. The network access node of any preceding claim wherein the processor and memory are further configured to perform:receiving an indication of whether or not emergency calls should be enabled.

10. The network access node of any preceding claim wherein the processor and memory are further configured to perform:receiving, from a user equipment (UE) located in a cell, a connection request; determining that no core network node has yet been assigned for this UE;45determining the preferred network slice for emergency calls for the current cell or tracking area comprising the cell;selecting a core network node to send the request to, based on at least the determined preferred network slice for emergency calls.11 . The network access node of any of claims 1 to 9 wherein the processor and memory are further configured to perform:receiving, from a user equipment (UE) located in a cell, a connection request; determining the preferred network slice for emergency calls for the current cell or current tracking area comprising the cell;determining the identity of a core network node which has already been assigned for this UE and that the assigned core network node does not support the determined preferred network slice for emergency calls; andbased on the determining that the core network node does not support the determined preferred network slice, sending a message to the core network node comprising relocation information.

12. The network access node of any claims from 1 to 9 wherein the processor and memory are further configured to perform:determining that a received connection request from a UE is for an emergency call setup and that the UE has an assigned core network node which does not support the preferred network slice for current cell or tracking area of the UE;based on the determining, sending a message to the core network node comprising relocation information.

13. The network access node of claim 11 or 12 wherein the relocation information comprises at least one of:a request to relocate the UE to another core network node;an indication of a preferred network slice for emergency calls;an indication of a supported network slice for emergency calls;an identity of another core network node to which the UE is requested to be relocated.

14. The network access node of any claims from 1 to 9 wherein the processor and memory are further configured to perform:determining that a received connection request from a UE is for an emergency call setup and that the UE has an assigned core network node which does not support the preferred network slice for emergency calls for the current cell or tracking area; based on the determining, sending a message to another core network node, the message comprising at least one:a request to fetch UE context from the assigned core network node;an indication of a preferred network slice for emergency calls;an indication of a supported network slice for emergency calls;an identity of the assigned core network node from which the UE context is to be fetched.

15. The network access nodes of any of claims 11 to 14 wherein the processor and memory are further configured to perform:exchanging information with one or more neighboring network access nodes wherein the exchanged information comprises at least one:indication of supported network slices for emergency calls for respective cells; indication of supported network slices for emergency calls for respective tracking areas;indication of preferred network slices for emergency calls for respective cells; indication of preferred network slices for emergency calls for respective tracking areas.

16. The network access node of any of claim 15 wherein the processor and memory are further configured to perform:sending the exchanged information from the neighboring network access nodes to the core network node.

17. A core network node comprising:at least one processor;and at least one memory storing instructions that, when executed by the at least one processor, cause the core node at least to perform:receiving an indication of network slices configured for support of an emergency call, from a network access node;configuring at least one network slice from the network access node for emergency calls wherein the configured network slices comprise at least one of the indicated supported network slices; andproviding the emergency network slice configuration of the at least one network slice to the network access node.

18. The core network node of claim 17 wherein the processor and memory are further configured to enable the core network node to:receive, from the network access node, an indication of preference associated with the indicated slices configured for support of an emergency call;select the emergency network slice to be configured for emergency calls based, at least in part, on the indication of preference.

19. The core network node of any of claims 17 to 18 wherein the at least one network slice that is configured for emergency call is selected based, at least in part, on the network slices supported by the core network node.

20. The core network node of any of claims 17 to 19 wherein a list of network slices supported by the core network node is received from an operations and maintenance system21. The core network node of any of claims 17 to 20 wherein the processor and memory are configured to enable the core network node to determine if emergency calls are allowed; andconfigure the network slice for emergency calls if emergency calls are allowed; orprovide an indication to the network access node that emergency calls are not allowed if emergency calls are not allowed.

22. The core network node of any of claims 17 to 21 wherein receiving the indication of network slices configured for support of an emergency call from the network access node further comprises at least one of the following:receiving the indication of network slices configured for support of an emergency call for respective cells;receiving the indication of network slices configured for support of an emergency call for respective tracking areas.

23. The core network node of any of claims 17 to 22 wherein configuring at least one network slice from the core network node for emergency calls wherein the configured48network slices are at least one of the indicated supported network slices further comprises at least one of the following:configuring the at least one network slice for respective cells;configuring the at least one network slice for respective tracking areas.

24. The core network node of any of claims 17 to 23 wherein the processor and memory are configured to enable the core network node to provide an indication of whether or not emergency calls are enabled for a given cell or tracking area.

25. The core network node of any of claims 17 to 24 wherein the processor and memory are further configured to enable the core network node to perform:receiving a connection message associated with a UE from a network access node, the connection message comprising at least one of:an indication of one or more network slices configured for support of an emergency call in the cell of the UE;an indication of one or more network slices configured for support of an emergency call in the tracking area of the UE;an indication of one or more network slices preferred for support of an emergency call in the cell of the UE;an indication of one or more network slices preferred for support of an emergency call in the tracking area of the UE;a request for relocation of the UE context to another core network node; an indication of at least one other core network node onto which the UE context can be relocated;determining, based at least in part on the connection message, to relocate the UE context to another core network node; andsending a request for relocation of UE context at least to one of; the network access node or the another core network node.

26. A core network node comprising: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 at least to perform:receiving a request for UE context relocation from an initial core network node, the request comprising at least one of:an indication of at least one network slice configured for support of an emergency call; or49an indication to update the UE with an updated allowed list of network slices for emergency calls:sending to the UE a message comprising an updated allowed list of network slices for emergency calls.

27. A core network node as claimed in claim 26 wherein the request for UE context relocation comprises a connection message associated with the UE and the processor and memory are further configured to enable the core network node to perform:forwarding the connection message towards a session management function.

28. A core network node comprising: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 at least to perform:receiving a connection message associated with a UE from a network access node, the connection message comprising at least one of:an indication of at least one network slice configured for support of an emergency call;an indication of emergency call;an indication to update the UE with an updated allowed list of network slices for emergency calls;an indication to fetch a UE context from another core network node; an identification of a core network node from which the UE context is to be relocated;based on the received connection message, fetching the UE context from the identified core network node;sending to the UE a message comprising an updated allowed list of network slices for emergency calls for the UE.

29. A user equipment (UE) comprising:at least one processor;and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to perform:receiving, from a network access node, an indication of one or more network slices configured for support of emergency calls in a current cell or tracking area of the UE;50determining that none of the indicated network slices is in an allowed list of network slices for supporting an emergency call for the UE; andsending a registration request to a core network node via a network access node to enable adding at least one of the indicated network slices into the allowed list for the UE.

30. The UE of claim 29 wherein the processor and memory are configured to enable the UE to receive a response to the registration request comprising at least of the indicated network slices in the allowed list for the UE.

31. The UE of any of claims 29 to 30 wherein the indication of one or more network slices configured for support of emergency calls in the current cell is received from the network access node in a broadcast message.

Images