WO2023104527A1

WO2023104527A1 - Methods, communications devices, and wireless communications networks

Info

Publication number: WO2023104527A1
Application number: PCT/EP2022/083057
Authority: WO
Inventors: Vivek Sharma; Yuxin Wei; Yassin Aden Awad; Hideji Wakabayashi
Original assignee: Sony Group Corporation; Sony Europe B.V.
Priority date: 2021-12-06
Filing date: 2022-11-23
Publication date: 2023-06-15

Abstract

A method of operating a communications device configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network is provided. The method comprises receiving, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and determining, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Description

METHODS, COMMUNICATIONS DEVICES, AND WIRELESS COMMUNICATIONS NETWORKS

BACKGROUND

Field of Disclosure

The present disclosure relates to communications devices operating in wireless communications networks, and to such wireless communications networks.

The present application claims the Paris Convention priority from European patent application number EP21212621.3 filed on 6 December 2021, the contents of which are hereby incorporated by reference.

Description of Related Art

The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.

Latest generation mobile telecommunication systems are able to support a wider range of services than simple voice and messaging services offered by earlier generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

Future wireless communications networks will be expected to efficiently support communications with an ever-increasing range of devices and data traffic profiles than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communications devices, high resolution video displays, virtual reality headsets and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance.

In view of a desire to support new types of devices with a variety of applications there is expected to be a desire for future wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements.

As is well understood, various wireless telecommunications networks, such as LTE-based networks and NR-based networks, support different Radio Resource Control (RRC) modes for terminal devices, typically including: (i) RRC idle mode (RRC IDLE); and (ii) RRC connected mode

(RRC CONNECTED). When a terminal device transmits data, RRC connected mode is generally used. The RRC idle mode, on the other hand, is for terminal devices which are registered to the network (EMM-REGISTERED), but not currently in active communication (ECM-IDLE).

In order for a core network to maintain knowledge of the location of terminal devices in idle mode, the wireless networks referred to above generally utilise tracking areas or registration areas defined by operators in order to track terminal devices to a particular geographical region consisting of a number of cells. A terminal device may roam within this tracking/registration area without transmitting update messages to the core network and as such the core network may be aware of the tracking area or registration area in which a terminal device in idle mode is located.

However, tracking areas and registration areas generally cover a large geographical area and therefore do not provide the core network with a precise indication of the location of an idle mode terminal device. Without more precise knowledge of an idle mode terminal device’s location, it can be difficult or even impossible to implement certain network features. Furthermore, tracking and registration areas are generally defined when the wireless telecommunications networks are deployed and as such it is an extensive and difficult job for network operators to adjust tracking and registration areas in existing networks.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of the issues discussed above.

Embodiments of the present technique can provide a method of operating a communications device configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network. The method comprises receiving, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and determining, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Embodiments of the present technique, in addition to methods of operating communications devices, also relate to communications devices, wireless communications networks, methods of operating wireless communications networks, and circuitry for communications devices and wireless communications networks.

Respective aspects and features of the present disclosure are defined in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

Figure 1 schematically represents some aspects of an LTE-type wireless telecommunication system which may be configured to operate in accordance with certain embodiments of the present disclosure;

Figure 2 schematically represents some aspects of a new radio access technology (RAT) wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure; Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

Figure 4 is a part schematic representation, part message flow diagram of communications between a communications device and a wireless communications network in accordance with embodiments of the present technique;

Figure 5 illustrates an example relationship between cells, tracking areas (TAs) and secondary tracking areas (STAs) in accordance with embodiments of the present technique; and

Figure 6 is a message flow diagram illustrating example communications between a UE, core network, and radio access network in accordance with embodiments of the present technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution Advanced Radio Access Technology (4G)

Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Holma H. and Toskala A [1], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

The network 6 includes a plurality of base stations 1 connected to a core network 2. Each base station provides a coverage area 3 (i.e. a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network (RAN).

Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e. page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

New Radio Access Technology (5G)

An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 30.

The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 such as that shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G/NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

Tracking Areas (TAs) and Additional Network Features

A Tracking Area (TA) is a collection of cells covering a particular geographical area where a UE can roam in idle mode, without being required to send update messages or other signalling to the core network. In other words, when a UE is in an idle mode (i.e. an RRC idle state), the location of the UE is known at the TA level. A UE may be configured with a specific TA (or list of TAs) which it can move between in idle mode. A TA might, for example, consist of ten cells, where a UE roaming within these ten cells is not required to send tracking updates to the network. In this manner, the quantity of signalling the UE is required to perform when in an idle mode is reduced.

In order for a UE to register to a TA, a base station may broadcast a TA identifier for the TA in which the base station (i.e. the cell provided by the base station) is included. The TA identifier may, for example, be included in system information broadcast by the base station for receipt by UEs, and use hexadecimal values to do so where 0000 and FFFE are reserved. The UE may then register with the base station and (for example, as part of the registration procedure) report the identifier of the TA to which it is connected to the core network (via the base station). In this manner, the core network is aware of the TA to which the UE is connected.

In LTE networks, when a UE moves out of a TA the UE sends a TA update message to the core network. Accordingly, the core network continues to be aware of the TA to which a UE is connected. There is no TA update procedure currently in 5G networks, which instead in a similar manner may use a Registration Area (RA) procedure, where a Registration Area consists of one or more TAs. RA information may be exchanged between the core network and UEs during a Non-Access Stratum (NAS) registration procedure. An RA update procedure is triggered during initial registration (e.g. NAS registration) of a UE to a RA/TA, upon expiry of a timer for the UE to initiate the update procedure, and/or when the UE moves out of a TA.

For a UE in RRC idle mode, the core network is aware that the UE is present within the network, but the radio access network (RAN) part (comprising radio network infrastructure equipment such as the base stations 1 of Figure 1 and the TRPs 10 of Figure 2) is not. The core network is aware of the location of idle mode UEs at a paging tracking area level but not at the level of individual transceiver entities, because the UE does not have a unique identifier within a cell (C-RNTI). The core network will generally assume a UE is located within the tracking area(s) associated with a transceiver entities most recently used for communicating with the UE, unless the UE has since provided a specific tracking area update (TAU) to the network. (As is conventional, idle mode UEs are typically required to send a TAU when they detect they have entered a different tracking area to allow the core network to keep track of their location.) Because the core network tracks UEs at a tracking area level, it is generally not possible for the network infrastructure to know which specific transceiver entities (radio network node) to use when seeking to initiate contact with a UE in idle mode.

Consequently, and as is well known by the person skilled in the art, when a core network is required to connect to an idle mode UE a paging procedure is used. Paging messages (i.e. signals) are transmitted to the base stations within the TA/RA in which the UE is located, where the paging messages are transmitted to all UEs within the cells of the TA/RA. UEs in idle mode periodically monitor for such paging messages and decode received paging messages to determine if the paging message is intended for itself. For UEs operating in a discontinuous reception (DRX) mode this occurs each time they wake up for their DRX active time. Paging signals for a specific terminal device are transmitted in defined frames (Paging Frames) / sub-frames (Paging Occasions) which are derived from the International Mobile Subscriber Identifier (IMSI) of the terminal device, as well as paging related DRX parameters established in system information transmitted within the network.

In idle mode, a UE is addressed by first paging the cells within the tracking area. The UE monitors for P- RNTI (paging identifier) on PDCCH rather than C-RNTI as it does in the RRC connected state. The paging message which is received following P-RNTI detection contains the UE identity, and if the UE receives this it will then respond by establishing an RRC connection and having a C-RNTI assigned.

Due to the manner in which paging messages are sent to UEs, the size (i.e. number of cells) of a TA is important. A large TA results in increased UE power consumption due to being required to decode paging messages for potentially a large number of UEs. Conversely, a small TA results in a large paging signaling load within the core network, as paging messages for various UEs are sent to a large number of TAs - while less power intensive for UEs, this may however be burdensome for particularly mobile UEs. However, in most cases TAs will be fixed by the core network, as these would have been established when the 5G network was deployed, and so therefore it can be a challenging and extensive task for an operator to adjust TAs, particularly after various additional features are considered in the network.

An example of such a possible additional feature is network slicing. Essentially, a network slice is a virtual independent end-to-end network that can be treated individually as compared to other slices, although all slices form part of the same overall physical network infrastructure, and are separated only in logical terms. Currently, it is understood that a slice will be available throughout the whole of a TA. Work in 3GPP Rel-17 on slicing enhancement focusses on the selection of a frequency based on slice priority. The slice info (for a single slice or for a slice group) that was agreed to be provided to the UE in a recent RAN2 meeting [2], using both broadcast and dedicated signaling, is provided for the serving frequency as well as for neighboring frequencies. Such slice-based and slice priority-based cell/frequency (re)selection in Access Stratum (AS):

• Step 0: NAS layer at UE provides slice information to AS layer at UE, including slice priorities;

• Step 1 : AS sorts slices in priority order starting with highest priority slice;

• Step 2: Select slices in priority order starting with the highest priority slice;

• Step 3: For the selected slice assign priority to frequencies received from network;

• Step 4: Starting with the highest priority frequency, perform measurements (same as legacy);

• Step 5: If the highest ranked cell is suitable (as defined in [3]) and supports the selected slice in step 2 then camp on the cell and exit this sequence of operation (it is for further study how the UE determines whether the highest ranked cell supports the selected slice);

• Step 6: If there are remaining frequencies then go back to step 4; Step 7: FFS: If the end of the slice list has not been reached go back to step 2; and Step 8: Perform legacy cell reselection.

As such, it can be understood that Rel-17 addresses a case where a slice is available on a particular frequency only. Rel-17 does not however address cases where, for example, an access and mobility function (AMF) does not support or is not upgraded to support a certain slice, or where a cell is not upgraded to support a certain slice, or where a particular slice is supported in a neighbouring TA but not in the TA in which a UE actually attempted registration. Also, work has been done within 3GPP on slicespecific access control via a network slice admission control (NSAC) function, and it is currently understood that a service request may simply be rejected if the slice via which the service is requested is overloaded. It may also be the case that a slice is supported over a restricted geographical area (e.g. within a factory, a stadium, or a home) but the network may also support a service associated with that slice may be outside of the restricted geographical area. However, if the slice is overloaded, then the network may support the service outside of the restricted geographical area only with reduced QoS requirements, e.g. so as to ensure a higher QoS over the slice within the restricted geographical area, and so the decision may not be purely about accepting or rejecting a service request. Furthermore, a particular slice may not be supported in a cell due to the control of one of operation and maintenance (0AM) or mobility management (MM). Yet further, it has not currently been addressed how network control may operate with respect to controlling UE behaviour for registration and deregistration whilst operating (or seeking to operate) on a particular network slice. Embodiments of the present disclosure seek to address one or more of these issues.

In addition to these issues, the features relating to slicing require UEs to be tracked over a finer granularity than that of a cell/TA. The present inventors have recognised that cell-level granularity will likely allow the core network to be aware of RAN topology, which may be problematic since the core network and RAN operators are likely to be different. This would also go against one of the design principles of 3GPP, in that the core network should not be aware of RAN topology (this was the case in 2G but was avoided in 3G and onwards).

Embodiments of the present technique propose that an identifier defining groups of cells similarly to a TA but having a finer granularity is a solution to at least some of those issues described above. In other words, a finer granularity TA may cover one or more cells within (i.e. as a subset of) a TA, one or more cells across different TAs, or could even cover the cases where it has a finer granularity than that of a cell; i.e. covering an area within a cell (but not the entirety of that cell).

Slicing Enhancements with a Finer Granularity of Tracking Areas

Figure 4 provides a part schematic representation, part message flow diagram of communications within a wireless communications system 60 between a communications device or UE 61 and a wireless communications network in accordance with embodiments of the present technique. The wireless communications network may include an infrastructure equipment 62 which provides and controls a first cell having a coverage area within in one of which the communications device 61 may be located, or may enter in and out of. The communications device 61 comprises a transceiver (or transceiver circuitry) 61.1 configured to transmit signals to or receive signals from the wireless communications network (for example, to the infrastructure equipment 62 via a wireless access interface provided by the wireless communications network), or indeed from other wireless communications networks, and a controller (or controller circuitry) 61.2 configured to control the transceiver circuitry 61. 1 to transmit or to receive the signals. As can be seen in Figure 4, the infrastructure equipment 62 may also comprise a transceiver (or transceiver circuitry) 62. 1 which may be configured to transmit signals to or receive signals from the communications device 61 via the wireless access interface, and a controller (or controller circuitry) 62.2, which may be configured to control the transceiver circuitry 62. 1 to transmit or to receive the signals. Each of the controllers 61.2, 62.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

The controller circuitry 61.2 of the communications device 61 is configured in combination with the transceiver circuitry 61.1 of the communications device 61 to receive 64, from the wireless communications network (e.g. from the infrastructure equipment 62), an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and to determine 66, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Essentially, embodiments of the present technique propose the introduction of a secondary TA (which may alternatively be implemented as a secondary RAN notification area (RNA) or some other similar identifier.

Figure 5 shows an example which illustrates an example relationship between cells, TA, and STAs in accordance with embodiments of the present technique. As can be seen in Figure 5, a plurality of TAs 70, 71 may each comprise a number of cells (while seven cells are shown in each TA 70, 71 in the example of Figure 5, those skilled in the art would appreciate that this is in no way limiting). The cells in TAs 70, 71 may also form part of STAs 72, 73, 74, where STAs 73 and 74 may each comprise just one cell (cells 76 and 77 respectively), while STA 72 may comprise a plurality of cells (e.g. 75 and 78). Again, those skilled in the art would appreciate that the number of cells comprised by each STA may be more than two, and that STAs may comprise cells from one TA only or cells from across TAs. Indeed, as can be seen in Figure 5, STA 72 comprises cells from across TAs 70 and 71, with one cell 75 being within one TA 70, and the other cell 78 being within another TA 71. Some cells may support a certain network slice or network slices, such as cells 75, 76, and 77 (shown via the dashed pattern), while other cells, such as cell 78, may not support such network slice(s). Some cells may be connected to access and mobility functions (AMFs), such as AMF 79 connected to cell 77. Some AMFs may support one or more of the network slices supported by the cell they are connected to, although some other network slices may not be supported by the AMF.

Although not shown in the example of Figure 5, a STA could be defined at the sub-cell level (i.e. cover a portion of one (or more) cells, but not the entirety of those cell(s)) and could therefore identify a UE based on the UE’s location and by creating a zone within a cell. In other words, the STA comprises only a part of each of the one or more cells. Here, the part of the cell(s) not forming part of that STA may form part of one or more other STAs, such that the granularity of the STAs is finer than that of the cells.

As such, a STA could be defined by either a combination of one or more vehicle-to-everything (V2X) zone ID(s) or global navigation satellite system (GNSS) locations. Alternatively, an STA could be implemented by ranging signals and/or wireless local area network (WLAN) signals confined within an area (e.g. identifying an indoor location), or by a specific beam coverage area (as NR supports directional beams within a gNB’s coverage). A confined area may have one or more associated WLAN signals, and the UE may help the core network/gNB to create a map of the confined area by reporting WLAN signals. Ranging signals received at the UE may define a perimeter of a certain distance, and this distance may be configured by the network either with or without user assistance. The gNB may also be able to access such information directly from a location management function (LMF) in the core network if service based architecture is supported for the RAN-core network interface.

If an unmanned aerial vehicle (UAV) application is available via a particular slice, then an STA could be defined for a three dimensional-based zone. Vertical scale can be identified based on a UE’s altitude sensor or 3D beamforming direction. The UAV flight direction could be different depending on the altitude level configured by UAV traffic control. For example, UAVs at high altitude may be configured to go eastbound, while those at low altitude may be configured to go westbound. Overlapped STAs in the same geographical zone may be defined, where one is for low altitude, and the other is for high altitude. For example, UAVs at high altitude may register with STA#1, while UAVs at low altitude may register with STA#2. The UE may decide the STA based on cell coverage (or geographical area) and/or altitude level.

As shown in the example of Figure 5, some cells may be connected to an AMF which does not support a certain slice, and it is recognised that such cells should be somehow identified. Some cells may not support certain slices within a TA, and these too should be known to the core network. In another example, a TA itself may not support a particular slice, but the same slice may be available in a neighbouring TA. In this case, a UE should be able to select an appropriate cell, and one option for the UE to be able to do this is that an STA may span over multiple TAs and include more than a single cell as shown in the example of Figure 5 with respect to STA 72. Embodiments of the present technique define solutions for at least the following issues, as discussed above:

• A slice may not be supported in a cell due to 0AM, mobility or NSAC;

• An AMF in a TA may not support a slice;

• A slice may be available in another TA of a registration area but not in the TA where a UE attempted registration; and

• How should the network control UE behaviour for registration and deregistration.

A cell may not support a particular slice, for example when 0AM has prohibited it or when the cell is not upgraded and is a handover target cell. Alternatively, slice specific access control, NSAC, may reject the service request when, for example, the slice is overloaded. For at least these cases, an operator may define a STA which should be able to uniquely distinguish a cell/area within a TA. In other words, the STA may comprise no more than one cell associated with each of the one or more TAs. Here, the STA may comprise an area within a cell, only a single cell from a single TA, or may comprise multiple cells, each from different TAs.

If each cell within a TA is assigned a different STA, then cells which do not support a slice can be configured via 0AM to the core network (through indicating that cell’s STA) and the core network is then able to use this information to configure allowed STAs for a UE within a TA in NAS registration signaling, without needing to be aware of the RAN topology.

In some arrangements of embodiments of the present technique, the NSAC procedure may be enhanced to indicate to a UE information for use in determining how it should operate when access has been rejected for a slice, for example by then selecting another STA for the same slice. This information may be broadcasted. This may be done to ensure slice connectivity is available for a given slice for a UE, though this may be with a reduced QoS in case slice resources are overloaded and the network operator does not want to lose revenue and service. In other words, the communications device may be configured to transmit (e.g. to the infrastructure equipment), to the wireless communications network, a first service request over a first of the network slices associated with the STA, to receive, from the wireless communications network (e.g. from the infrastructure equipment), an indication that the first service request has been rejected due to the first cell/area within the first cell not supporting the first network slice, to receive, from the wireless communications network (e.g. from the infrastructure equipment), an indication of one or more other STAs each being associated with the first network slice and comprising one or more second cells of the wireless communications network which support the first network slice, and to transmit, to the wireless communications network (e.g. to the infrastructure equipment), a second service request over the first network slice in one of the second cells.

Alternatively, as can be understood with reference to the example of Figure 5 (specifically with reference to STA 72 spanning TAs 70 and 71), a slice for which the UE is rejected a service request over may not be available in a first TA, but may then be available in a second TA. For example, cell 78 in STA 72 and TA 71 may not support the slice, and here the UE may receive a service reject message. However, in accordance with some arrangements of embodiments of the present disclosure, the UE is able to instead select cell 75 which does support the slice. In other words, the first cell may not support at least one of the network slices, and wherein a second cell may support the at least one network slice, the second cell being in the same STA as the first cell but in a different TA to the first cell.

Hence, in such arrangements of embodiments of the present disclosure the UE may be configured to select a new cell in the same STA (but different TA) for the same slice upon NSAC rejecting the UE’s service request for that slice in a first cell. In other words, the communications device may be configured to transmit, to the wireless communications network, a first service request over a first of the network slices associated with the STA, to receive, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and to transmit, to the wireless communications network, a second service request over the first network slice in a second cell, wherein the second cell is in the same STA as the first cell but in a different TA to the first cell.

Alternatively, the UE may be configured in accordance with some arrangements of embodiments of the present disclosure simply, upon NSAC rejecting the UE’s service request over a first slice, to select a new slice (for example if this new slice is able to provide the same service for which the UE was rejected by NSAC over the first slice). In other words, the communications device may be configured to transmit, to the wireless communications network (e.g. to the infrastructure equipment), a first service request over a first of the network slices associated with the STA, to receive, from the wireless communications network (e.g. from the infrastructure equipment), an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and to transmit, to the wireless communications network (e.g. to the infrastructure equipment), a second service request over a second of the network slices associated with the STA.

An STA can be specified for a cell connecting to an AMF which is not upgraded, as described with reference to Figure 5 where cell 77 is connected to AMF 79. The area affected by such a non-upgraded AMF may have a separate STA. In accordance with some arrangements of embodiments of the present disclosure, the mapping between the Network Slice Selection Assistance Information (NSSAI) and STAs, configured in NAS registration procedure, may be able to distinguish such cells/areas. In other words, the indication of the STA may indicate that the cells of the STA are connected to an access and mobility function, AMF, wherein the AMF either supports or does not support the one or more network slices associated with the STA (where the indication of the STA may further indicate whether or not the AMF that the STA’s cells are connected to supports the network slice(s) associated with the STA). Similarly to the issue with certain cells not supporting a slice, it is considered that an STA could overlap between two TAs (e.g. STA 72 spanning TAs 70 and 71 in the example of Figure 5 as described above) so that such a situation of a non-upgraded AMF can be avoided.

Furthermore, through effective assignment of a different STA to each cell in a TA, the network may be able to control registration/deregistration in a conventional manner for each UE individually.

Figure 6 describes an example of an overall procedure involving the core network (CN) 83, (a cell of a) RAN 82, and UE 81 in accordance with some arrangements of embodiments of the present technique. It is important here that there is a known and defined mapping between allowed slices and STAs. One option for implementing this is that such a mapping between STAs and network slices may be configured within a registration accept message (during registration of the UE 81) or any other suitable message used to update slice information at the UE 81. The exemplary overall procedure of Figure 6 is as follows:

• Step SE A secondary TA may be configured differently for each cell in a TA. Alternatively, an STA may be configured for a selection of cells in the TA (e.g. a subset of such cells in a TA, but not all of them). This configuration of the mapping between STAs and cell IDs is implemented in a similar manner to TAs (i.e. the operator database (0AM) used for TA assignment is upgraded to assign STAs to individual cells). This configuration is then provided to the core network 83. Alternatively, the 0AM configures a mapping between STAs and each cell on the RAN 82 side, and the RAN 82 sends the configured STA to cell mapping to the core network using, for example, the NG SETUP procedure during the interface setup between the CN 83 and gNB;

• Steps S2/S3: Based on the STA configuration in step SI, the gNB should be aware of the STA to cell mapping and will therefore be ready to broadcast an STA value in system information for any UEs 81 connected to/selecting/reselecting its cell;

• Step S4: The UE 81, based on receiving an STA value in system information and an STA value separately received from the core network 83 during registration procedure, checks if the STA is allowed (i.e. by comparing the STA values). If the STA is allowed, then UE 81 camps on the cell. If no mapping configuration exists between the STA and the cell ID, and/or the STA and the slice ID, then the UE 81 initiates a NAS registration procedure;

• Steps S5/S6: The UE 81 initiates an existing NAS registration request in step S5. Here, the core network 83 may at this stage configure the mapping between STA and allowed slices, and indicate this to the UE 81 in step S6. The core network 83 may receive STA configuration information from other entities like LMF, sensing server, or WLAN AP mapping server, etc. for cases where the STA is smaller than a cell;

• Step S7 : The UE 81 camps on the cell for which both STA and slice ID match with respect to the configured values (from CN 83) and the received value (from system information) in steps S2 and S3;

• Steps S8/S9/S10: The UE 81 receives NSSAI and Secondary TA association from the core network 83 and in step S8 the UE 81 reports the ID of the Secondary TA to the RAN 82. In other words, the communications device may be configured to transmit, to the wireless communications network (e.g. to the infrastructure equipment/gNB), an indication of an identity of the STA. This may be reported in msg 5, and may subsequently be used by the RAN 82 for AMF selection. The RAN 82 will then in step S9 select an appropriate AMF based on the newly received ID. In other words, the network may then be configured to select an appropriate AMF based on the received indications from the communications device, and to transmit, to the communications device, an indication of the selected AMF. Currently, AMF is selected based on NSSAI for slice support. This AMF selection is then signalled by the RAN 82 to the CN 83 in step S10;

• One or more STAs which are supported by one or more neighbouring cells may additionally be reported by the UE 81 to the network (e.g. to the UE’s serving cell), for the purposes of neighbour cell relations for Self-Organising Network-Automatic Neighbour Relations (SON- ANR), so that the situation described above (i.e. whether a UE is allowed to camp on a cell based on its STA and/or IDs of slices available on that cell) can be avoided in advance during handover, for example. In other words, the communications device may be configured to transmit, to the wireless communications network (e.g. to the infrastructure equipment/gNB), an indication of one or more other cells of the STA to the first cell (i.e. one or more neighbouring cells which also form part of and thus support that STA). For a UE with knowledge of more than one STA, this may be done for each of those STAs.

Those skilled in the art would appreciate that the example procedure described above with reference to Figure 6 is merely an example of arrangements of embodiments of the present technique. In other examples, further steps may be performed, or some of steps SI to S 10 may not be performed, or may differ from the way in which they have been described above.

From the RAN’s point of view, the secondary TA can be broadcast in SIB1 or any other SIB along with existing cell access related information. In other words, the indication of the STA is received via system information broadcasted by the wireless communications network. The STA may be signalled along with the TA, because the secondary TA will also become a part of the cell access restriction check. As also mentioned above, the UE receives an STA value from the NAS layer during, for example, a registration procedure performed with the core network. In other words, the indication of the STA is additionally received via non access stratum, NAS, layer signalling from the wireless communications network.

In arrangements of embodiments of the present disclosure, if the UE has a match between the secondary TA value received from the NAS layer and the secondary TA value broadcast from a particular cell, then the UE selects that cell. On the other hand, if the UE does not have a match between the secondary TA value received from the NAS layer and the secondary TA value broadcast from a particular cell, then the UE shall not select that cell. In other words, the communications device is configured to determine if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling. Here, the communications device may be configured to either select the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling, or to select a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information does not match the indication of the STA received via the NAS signalling, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell.

In arrangements of embodiments of the present technique, the first cell may be configured to broadcast the STAs of neighboring cells, or alternatively, the UE may read target cell system information (which may comprise indications of a neighbouring cell’s own STA(s)) during a cell selection/reselection procedure to one of those neighbouring cells, so that the UE is able to check the STA availability and associated slice availability. Here, the UE may select the second cell either on another frequency based on the frequency priority list (already specified) or may select the second cell based on a received intra frequency reselection indicator (IFRI). In other words, the communications device may be configured to select the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via the system information, or to select the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via the system information. Though IFRI signalling is known in the art with respect to cell reselection, the new aspect applicable here to embodiments of the present technique is that the IFRI bit in system information is applicable to secondary TAs. While the behavior described above relates primarily to a UE undergoing a transition from Idle mode to Connected mode, UE mobility during idle/inactive mode can also take into account the secondary TA in the same manner. Furthermore, if the slice is a higher priority slice, then the UE may either select the second-best cell from the list either based on the IFRI bit or on the frequency priority list.

In accordance with some arrangements of embodiments of the present disclosure, if configured with a secondary TA/RNA, a UE moving out of a secondary TA may perform a secondary TA update procedure. In other words, the communications device may be configured to determine that the communications device is moving outside of the STA, and therefore determining that the communications device is to select a second cell for transmitting signals to and/or receiving signals from the wireless communications network instead of the first cell, the second cell being in a second STA, and to perform an STA update procedure based on the communications device selecting the second cell in the second STA. This procedure can be either a NAS or an AS/N2 procedure. Such UEs may be in any state, i.e. Idle, Inactive, or Connected.

In some arrangements of embodiments of the present disclosure, the UE may assume that a slice is not supported when moving out of an STA if the target cell STA is not in the allowed list. In other words, the communications device may be configured to determine whether or not the second STA is in an allowed list of STAs indicated via signalling information received from the wireless communications network, wherein the allowed list is associated with one of the network slices associated with the STA.

In at least some arrangements of embodiments of the present technique however, the network may provide service continuity in an area which is not in the allowed STA list, though this may be with a lower QoS than in areas which are in the allowed STA list. For example, such service continuity may be provided in a high-resolution video (e.g. 4K) conference application implemented by slicing. When a UE moves out a particular STA, the video resolution is downgraded (e.g. from 4K to HD) but the conference service is still continued for the user using that UE, for example with voice and lower-resolution video. A user (or a slicing operator or a network operator) may be provided with options regarding how to handle the service when a UE moves out of an STA, i.e. it may be possible to select between options such as whether the network stops the service or continues the service with a downgraded QoS.

In another arrangement of embodiments of the present disclosure, the network may provide a different paging configuration in an area which is not in the allowed STA list. In other words, the communications device may be configured to receive paging signals from the wireless communications network in accordance with a first configuration if the STA in which the communications device is located is in an allowed list of STAs, or to receive paging signals from the wireless communications network in accordance with a second configuration different to the first configuration if the STA in which the communications device is located is not in the allowed list. For example, for a machine type communications (MTC)/narrowband Internet of Things (NB-IoT) UE which is in the original STA, this UE may operate in an Mobile Initiated Connection Only (MICO) mode, which disables paging from the network. The UE therefore is able to save on power consumption FOR stand-by and the network may save resources that would otherwise be required for paging. For example, for primitive functions like an MTC UE sending small data in a fixed location, MICO is good enough. On the other hand, when the UE moves into a different STA from the original one, the UE may stop operating in the MICO mode, and register as a normal UE which is able to receive paging from the network. For example, if the UE is moving from its original location, it may need to track the status of external devices and network elements, and therefore paging is required. MTC may in this case be supported by a separate slice, and the UE have both MTC and normal operation capabilities.

In another arrangement of embodiments of the present disclosure, the STA may be added to a conditional handover (CHO) configuration. Here, if the UE encounters a cell with an allowed STA, then this may trigger the UE’s HO towards this cell. That is, a CHO execution condition in such arrangements may be that the cell’s STA is an allowed STA. In other words, the communications device may be configured to receive, from the wireless communications network, a conditional handover configuration, and to determine in accordance with the conditional handover configuration, if the second STA is in the allowed list, that the communications device should perform a handover procedure to connect to the second cell.

It may not be possible to upgrade existing base stations to support the broadcast of new STA values, due to the sheer number of base stations deployed in the network. However, both the core network and UEs need to be upgraded to support new features, especially NAS layer impacts. In this case, one option according to arrangements of embodiments of the present technique is that the operator derives the STA for a particular cell based on, for example, the TA value and the cell ID. In this case, the method to derive the STA from Cell ID and TA values should be standardised so that all UEs implement STA derivation the same way and without any ambiguity. For example, the STA could be derived:

• STA = Cell ID XOR TA;

• STA = Cell ID AND TA; or

• STA = TA mod 8.

Here, if the Cell ID is shorter in value than TA then either the most significant bits (MSBs) or least significant bits (LSB) of the TA (such that the number of bits for both the cell ID and TA are the same) is taken into account, or vice versa for the cell ID.

Alternatively, the STA may be configured in the UE by entities like LMF or a server hosting non-3GPP measurements (WLAN, Bluetooth (BT), sensing etc) or 3GPP defined sensing measurements and using either NAS or AS signalling which is transparent to both the AMF and RAN nodes (i.e. a container originating from the LMF or the server and carried over either NAS or AS signaling).

In accordance with embodiments of the present technique, the operator 0AM may calculate the STA value and inform the CN of this calculated value. In other words, the wireless communications network may be configured to determine the STA by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell, or the wireless communications network may be configured to determine the STA by performing a modulus operation on the TA comprising the first cell. Furthermore, the wireless communications network may then (or may otherwise if STA value broadcast is supported) be configured to transmit to a core network part of the wireless communications network, an indication of one or more STAs including the STA and an indication of one or more cells of the wireless communications network associated with each of the one or more indicated STAs. The network may then also include the derived STA value in NAS signaling transmitted to the UE. In other words, the wireless communication network may be configured to transmit the indication of the STA, after determining the STA by performing either the OR operation or the AND operation, via NAS layer signalling to the communications device. In a similar manner, the UE - when it encounters a new cell - may in accordance with arrangements of embodiments of the present technique try to derive the STA value based on Cell ID and TA values. In other words, the communications device may be configured to derive an STA value by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell, or the communications device may be configured to derive the STA value by performing a modulus operation on the TA comprising the first cell. If this derived value matches the value indicated by the core network in NAS signalling, then the UE may assume that the cell can support the new features. In other words, the communications device may be configured to determine if the indication of the STA received via the NAS signalling matches the derived STA value, and to select the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling matches the derived STA value.

If, on the other hand, the STA value derived by the UE does not match the value indicated by CN in NAS signaling, then UE can safely assume that this cell does not support the new features. In other words, the communications device may be configured to determine if the indication of the STA received via the NAS signalling matches the derived STA value, and to select a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling does not match the derived STA value, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell. If the STA is derived as part of a cell accessibility check (i.e. where the UE determines that it should not camp on a cell where the derived and received STA values do not match) then the UE does not camp on the cell with that STA value where the calculated STA value does not match the NAS signalled STA value.

Here, the UE may select another cell is based on either IFRI or frequency priority in the same manner as described above for UEs which received the indication of the STA in broadcasted system information. That is, the UE may select the second (other) cell either on another frequency based on the frequency priority list (already specified) or may select the second cell based on a received intra frequency reselection indicator (IFRI). In other words, the communications device may be configured to select the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via system information broadcast by the wireless communications network, or to select the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via system information broadcast by the wireless communications network.

Those skilled in the art would appreciate that the example system shown in Figure 4 and described with respect to the arrangements illustrated by Figures 5 and 6 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such methods or systems, or the steps may be performed in any logical order.

Those skilled in the art would further appreciate that such wireless communications networks and/or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such wireless communications networks and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure. The following numbered paragraphs provide further example aspects and features of the present technique:

Paragraph 1. A method of operating a communications device configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, the method comprising receiving, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and determining, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Paragraph 2. A method according to Paragraph 1, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and transmitting, to the wireless communications network, a second service request over a second of the network slices associated with the STA.

Paragraph 3. A method according to Paragraph 1 or Paragraph 2, wherein the STA comprises no more than one cell associated with each of the one or more TAs.

Paragraph 4. A method according to Paragraph 3, wherein the first cell does not support at least one of the network slices, and wherein a second cell does support the at least one network slice, the second cell being in the same STA as the first cell but in a different TA to the first cell.

Paragraph 5. A method according to Paragraph 3 or Paragraph 4, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and transmitting, to the wireless communications network, a second service request over the first network slice in a second cell, wherein the second cell is in the same STA as the first cell but in a different TA to the first cell.

Paragraph 6. A method according to any of Paragraphs 1 to 5, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, receiving, from the wireless communications network, an indication of one or more other STAs each being associated with the first network slice and comprising one or more second cells of the wireless communications network which support the first network slice, and transmitting, to the wireless communications network, a second service request over the first network slice in one of the second cells.

Paragraph 7. A method according to any of Paragraphs 1 to 6, wherein the indication of the STA indicates that the cells of the STA are connected to an access and mobility function, AMF, wherein the AMF either supports or does not support the one or more network slices associated with the STA. Paragraph 8. A method according to any of Paragraphs 1 to 7, wherein the indication of the STA is received via system information broadcasted by the wireless communications network.

Paragraph 9. A method according to Paragraph 8, wherein the indication of the STA is additionally received via non access stratum, NAS, layer signalling from the wireless communications network. Paragraph 10. A method according to Paragraph 9, comprising determining if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling, and selecting the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling.

Paragraph 11. A method according to Paragraph 9, or Paragraph 10 comprising determining if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling, and selecting a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information does not match the indication of the STA received via the NAS signalling, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell.

Paragraph 12. A method according to Paragraph 11, comprising selecting the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via the system information.

Paragraph 13. A method according to Paragraph 11 or Paragraph 12, comprising selecting the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via the system information.

Paragraph 14. A method according to any of Paragraphs 1 to 13, wherein the indication of the STA is received via NAS layer signalling from the wireless communications network.

Paragraph 15. A method according to Paragraph 14, comprising deriving an STA value by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or deriving the STA value by performing a modulus operation on the TA comprising the first cell, determining if the indication of the STA received via the NAS signalling matches the derived STA value, and selecting the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling matches the derived STA value.

Paragraph 16. A method according to Paragraph 14 or Paragraph 15, comprising deriving an STA value by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or deriving the STA value by performing a modulus operation on the TA comprising the first cell, determining if the indication of the STA received via the NAS signalling matches the derived STA value, and selecting a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling does not match the derived STA value, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell.

Paragraph 17. A method according to Paragraph 16, comprising selecting the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via system information broadcast by the wireless communications network.

Paragraph 18. A method according to Paragraph 16 or Paragraph 17, comprising selecting the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via system information broadcast by the wireless communications network.

Paragraph 19. A method according to any of Paragraphs 1 to 18, comprising transmitting, to the wireless communications network, an indication of the identity of the STA.

Paragraph 20. A method according to any of Paragraphs 1 to 19, comprising transmitting, to the wireless communications network, an indication of one or more other cells of the STA to the first cell.

Paragraph 21. A method according to any of Paragraphs 1 to 20, comprising determining that the communications device is moving outside of the STA, and therefore determining that the communications device is to select a second cell for transmitting signals to and/or receiving signals from the wireless communications network instead of the first cell, the second cell being in a second STA, and performing an STA update procedure based on the communications device selecting the second cell in the second STA.

Paragraph 22. A method according to Paragraph 21, comprising determining whether or not the second STA is in an allowed list of STAs indicated via signalling information received from the wireless communications network, wherein the allowed list is associated with one of the network slices associated with the STA.

Paragraph 23. A method according to Paragraph 22, comprising receiving, from the wireless communications network, a conditional handover configuration, and determining in accordance with the conditional handover configuration, if the second STA is in the allowed list, that the communications device should perform a handover procedure to connect to the second cell.

Paragraph 24. A method according to any of Paragraphs 1 to 23, wherein the STA comprises only a part of each of the one or more cells.

Paragraph 25. A method according to any of Paragraphs 1 to 24, comprising receiving paging signals from the wireless communications network in accordance with a first configuration if the STA in which the communications device is located is in an allowed list of STAs, or receiving paging signals from the wireless communications network in accordance with a second configuration different to the first configuration if the STA in which the communications device is located is not in the allowed list.

Paragraph 26. A communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and to determine, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Paragraph 27. Circuitry for a communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and to determine, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

Paragraph 28. A method of operating a wireless communications network configured to transmit signals to and/or to receive signals from a communications device, the method comprising transmitting, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

Paragraph 29. A method according to Paragraph 28, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and receiving, from the communications device, a second service request over a second of the network slices associated with the STA.

Paragraph 30. A method according to Paragraph 28 or Paragraph 29, wherein the STA comprises no more than one cell associated with each of the one or more TAs.

Paragraph 31. A method according to Paragraph 30, wherein the first cell does not support at least one of the network slices, and wherein a second cell does support the at least one network slice, the second cell being in the same STA as the first cell but in a different TA to the first cell.

Paragraph 32. A method according to Paragraph 30 or Paragraph 31, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and receiving, from the communications device, a second service request over the first network slice in a second cell, wherein the second cell is in the same STA as the first cell but in a different TA to the first cell.

Paragraph 33. A method according to any of Paragraphs 28 to 32, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, transmitting, to the communications device, an indication of one or more other STAs each being associated with the first network slice and comprising one or more second cells of the wireless communications network which support the first network slice, and receiving, from the communications device, a second service request over the first network slice in one of the second cells.

Paragraph 34. A method according to any of Paragraphs 28 to 33, wherein the indication of the STA indicates that the cells of the STA are connected to an access and mobility function, AMF, wherein the AMF either supports or does not support the one or more network slices associated with the STA.

Paragraph 35. A method according to any of Paragraphs 28 to 34, comprising broadcasting the indication of the via system information.

Paragraph 36. A method according to Paragraph 35, comprising additionally transmitting the indication of the STA via non access stratum, NAS, layer signalling to the communications device. Paragraph 37. A method according to any of Paragraphs 28 to 36, comprising determining the STA by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or determining the STA by performing a modulus operation on the TA comprising the first cell.

Paragraph 38. A method according to Paragraph 37, comprising transmitting the indication of the STA, after determining the STA by performing either the OR operation or the AND operation, via NAS layer signalling to the communications device.

Paragraph 39. A method according to any of Paragraphs 28 to 38, comprising controlling registration and/or deregistration of the communications device with the wireless communications network based on the indicated STA.

Paragraph 40. A method according to any of Paragraphs 28 to 39, comprising transmitting, to a core network part of the wireless communications network, an indication of one or more STAs including the STA and an indication of one or more cells of the wireless communications network associated with each of the one or more indicated STAs.

Paragraph 41. A method according to any of Paragraphs 28 to 40, comprising receiving, from a core network part of the wireless communications network, an indication of the association between the STA and one or more network slices of the wireless communications network. Paragraph 42. A method according to any of Paragraphs 28 to 41, comprising receiving, from the communications device, an indication of the identity of the STA, selecting an appropriate AMF based on the received indication from the communications device, and transmitting, to the communications device, an indication of the selected AMF.

Paragraph 43. A method according to any of Paragraphs 28 to 42, comprising receiving, from the communications device, an indication of one or more other cells of the STA to the first cell.

Paragraph 44. A method according to any of Paragraphs 28 to 43, wherein the STA comprises only a part of each of the one or more cells.

Paragraph 45. A method according to any of Paragraphs 28 to 44, comprising transmitting paging signals to the communications device in accordance with a first configuration if the STA in which the communications device is located is in an allowed list of STAs, or transmitting paging signals to the communications device in accordance with a second configuration different to the first configuration if the STA in which the communications device is located is not in the allowed list.

Paragraph 46. A wireless communications network comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

Paragraph 47. Circuitry for a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

Paragraph 48. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Paragraphs 1 to 25 or Paragraphs 28 to 45.

Paragraph 49. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 48.

In so far as embodiments of the disclosure have been described as being implemented, at least in part, by software-controlled data processing apparatus, it will be appreciated that a non-transitory machine- readable medium carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure.

It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and/or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and/or processors may be used without detracting from the embodiments.

Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and/or processors.

Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

References

[1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[2] R2-2111444: “Change Request 38.331 CR Draft rev (current version 16.6.0)” (Huawei, HiSilicon), November 2021.

[3] TS 38.304, “NR; User Equipment (UE) procedures in idle mode and in RRC Inactive state (version 16.6.0)” (3GPP Organisation), September 2021.

Claims

CLAIMS What is claimed is:

1. A method of operating a communications device configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, the method comprising receiving, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and determining, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

2. A method according to Claim 1, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and transmitting, to the wireless communications network, a second service request over a second of the network slices associated with the STA.

3. A method according to Claim 1, wherein the STA comprises no more than one cell associated with each of the one or more TAs.

4. A method according to Claim 3, wherein the first cell does not support at least one of the network slices, and wherein a second cell does support the at least one network slice, the second cell being in the same STA as the first cell but in a different TA to the first cell.

5. A method according to Claim 3, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and transmitting, to the wireless communications network, a second service request over the first network slice in a second cell, wherein the second cell is in the same STA as the first cell but in a different TA to the first cell.

6. A method according to Claim 1, comprising transmitting, to the wireless communications network, a first service request over a first of the network slices associated with the STA, receiving, from the wireless communications network, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, receiving, from the wireless communications network, an indication of one or more other STAs each being associated with the first network slice and comprising one or more second cells of the wireless communications network which support the first network slice, and transmitting, to the wireless communications network, a second service request over the first network slice in one of the second cells.

7. A method according to Claim 1, wherein the indication of the STA indicates that the cells of the STA are connected to an access and mobility function, AMF, wherein the AMF either supports or does not support the one or more network slices associated with the STA.

8. A method according to Claim 1, wherein the indication of the STA is received via system information broadcasted by the wireless communications network.

9. A method according to Claim 8, wherein the indication of the STA is additionally received via non access stratum, NAS, layer signalling from the wireless communications network.

10. A method according to Claim 9, comprising determining if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling, and selecting the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling.

11. A method according to Claim 9, comprising determining if the indication of the STA received via the system information matches the indication of the STA received via the NAS signalling, and selecting a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the system information does not match the indication of the STA received via the NAS signalling, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell.

12. A method according to Claim 11, comprising selecting the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via the system information.

13. A method according to Claim 11, comprising selecting the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via the system information.

14. A method according to Claim 1, wherein the indication of the STA is received via NAS layer signalling from the wireless communications network.

15. A method according to Claim 14, comprising deriving an STA value by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or deriving the STA value by performing a modulus operation on the TA comprising the first cell, determining if the indication of the STA received via the NAS signalling matches the derived STA value, and selecting the first cell for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling matches the derived STA value.

16. A method according to Claim 14, comprising deriving an STA value by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or deriving the STA value by performing a modulus operation on the TA comprising the first cell, determining if the indication of the STA received via the NAS signalling matches the derived STA value, and selecting a second cell of the wireless communications network for transmitting signals to and/or receiving signals from the wireless communications network if the indication of the STA received via the NAS signalling does not match the derived STA value, wherein the second cell is a neighbouring cell to the first cell and is in a different STA to the first cell.

17. A method according to Claim 16, comprising selecting the second cell based on the second cell being highest in a frequency priority list of cells, wherein the frequency priority list is indicated via system information broadcast by the wireless communications network.

18. A method according to Claim 16, comprising selecting the second cell based on the second cell being indicated by an intra frequency reselection indicator, IFRI, wherein the IFRI is indicated via system information broadcast by the wireless communications network.

19. A method according to Claim 1, comprising transmitting, to the wireless communications network, an indication of the identity of the STA.

20. A method according to Claim 1, comprising transmitting, to the wireless communications network, an indication of one or more other cells of the STA to the first cell.

21. A method according to Claim 1, comprising determining that the communications device is moving outside of the STA, and therefore determining that the communications device is to select a second cell for transmitting signals to and/or receiving signals from the wireless communications network instead of the first cell, the second cell being in a second STA, and performing an STA update procedure based on the communications device selecting the second cell in the second STA.

22. A method according to Claim 21, comprising determining whether or not the second STA is in an allowed list of STAs indicated via signalling information received from the wireless communications network, wherein the allowed list is associated with one of the network slices associated with the STA.

23. A method according to Claim 22, comprising receiving, from the wireless communications network, a conditional handover configuration, and determining in accordance with the conditional handover configuration, if the second STA is in the allowed list, that the communications device should perform a handover procedure to connect to the second cell.

24. A method according to Claim 1, wherein the STA comprises only a part of each of the one or more cells.

25. A method according to Claim 1, comprising receiving paging signals from the wireless communications network in accordance with a first configuration if the STA in which the communications device is located is in an allowed list of STAs, or receiving paging signals from the wireless communications network in accordance with a second configuration different to the first configuration if the STA in which the communications device is located is not in the allowed list.

26. A communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and to determine, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

27. Circuitry for a communications device comprising transceiver circuitry configured to transmit signals to and/or to receive signals from at least a first cell of a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from the wireless communications network, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of the first cell, and to determine, based on the indication of the STA, an association between the STA and one or more network slices of the wireless communications network.

28. A method of operating a wireless communications network configured to transmit signals to and/or to receive signals from a communications device, the method comprising transmitting, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

29. A method according to Claim 28, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and receiving, from the communications device, a second service request over a second of the network slices associated with the STA.

30. A method according to Claim 28, wherein the STA comprises no more than one cell associated with each of the one or more TAs.

31. A method according to Claim 30, wherein the first cell does not support at least one of the network slices, and wherein a second cell does support the at least one network slice, the second cell being in the same STA as the first cell but in a different TA to the first cell.

32. A method according to Claim 30, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, and receiving, from the communications device, a second service request over the first network slice in a second cell, wherein the second cell is in the same STA as the first cell but in a different TA to the first cell.

33. A method according to Claim 28, comprising receiving, from the communications device, a first service request over a first of the network slices associated with the STA, transmitting, to the communications device, an indication that the first service request has been rejected due to the first cell not supporting the first network slice, transmitting, to the communications device, an indication of one or more other STAs each being associated with the first network slice and comprising one or more second cells of the wireless communications network which support the first network slice, and receiving, from the communications device, a second service request over the first network slice in one of the second cells.

34. A method according to Claim 28, wherein the indication of the STA indicates that the cells of the STA are connected to an access and mobility function, AMF, wherein the AMF either supports or does not support the one or more network slices associated with the STA.

35. A method according to Claim 28, comprising broadcasting the indication of the via system information.

36. A method according to Claim 35, comprising additionally transmitting the indication of the STA via non access stratum, NAS, layer signalling to the communications device.

37. A method according to Claim 28, comprising determining the STA by performing either an exclusive OR operation or an AND operation on an identifier of the first cell and an identifier of a TA comprising the first cell or determining the STA by performing a modulus operation on the TA comprising the first cell.

38. A method according to Claim 37, comprising transmitting the indication of the STA, after determining the STA by performing either the OR operation or the AND operation, via NAS layer signalling to the communications device.

39. A method according to Claim 28, comprising controlling registration and/or deregistration of the communications device with the wireless communications network based on the indicated STA.

40. A method according to Claim 28, comprising transmitting, to a core network part of the wireless communications network, an indication of one or more STAs including the STA and an indication of one or more cells of the wireless communications network associated with each of the one or more indicated STAs.

41. A method according to Claim 28, comprising receiving, from a core network part of the wireless communications network, an indication of the association between the STA and one or more network slices of the wireless communications network.

42. A method according to Claim 28, comprising receiving, from the communications device, an indication of the identity of the STA, selecting an appropriate AMF based on the received indication from the communications device, and transmitting, to the communications device, an indication of the selected AMF.

43. A method according to Claim 28, comprising receiving, from the communications device, an indication of one or more other cells of the STA to the first cell.

44. A method according to Claim 28, wherein the STA comprises only a part of each of the one or more cells.

45. A method according to Claim 28, comprising transmitting paging signals to the communications device in accordance with a first configuration if the STA in which the communications device is located is in an allowed list of STAs, or transmitting paging signals to the communications device in accordance with a second configuration different to the first configuration if the STA in which the communications device is located is not in the allowed list.

46. A wireless communications network comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

47. Circuitry for a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, an indication of a secondary tracking area, STA, wherein the STA comprises at least part of one or more cells of the wireless communications network, wherein the cells of the STA are a subset of cells of the wireless communications network which are associated with one or more tracking areas, TAs, and wherein the cells of the STA comprises at least part of a first cell with which the communications device is currently connected, wherein the indication of the STA indicates an association between the STA and one or more network slices of the wireless communications network.

48. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1 or Claim 28.

49. A non-transitory computer-readable storage medium storing a computer program according to Claim 48.