WO2024012863A1

WO2024012863A1 - Methods, communications devices, and infrastructure equipment

Info

Publication number: WO2024012863A1
Application number: PCT/EP2023/067437
Authority: WO
Inventors: Yuxin Wei; Vivek Sharma; Yassin Aden Awad; Hideji Wakabayashi; Samuel Asangbeng Atungsiri
Original assignee: Sony Group Corporation; Sony Europe B.V.
Priority date: 2022-07-13
Filing date: 2023-06-27
Publication date: 2024-01-18

Abstract

A method of operating a communications device configured to transmit signals to and/or to receive signals from a wireless communications network via a wireless radio interface provided by the wireless communications network is provided. The method comprises transmitting signals to and/or receiving signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, determining that one or more conditions to perform a mobility procedure have been satisfied, determining that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, performing the mobility procedure from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

Description

METHODS, COMMUNICATIONS DEVICES, AND INFRASTRUCTURE EQUIPMENT

BACKGROUND Field of Disclosure

The present disclosure relates to communications devices, infrastructure equipment and methods for the more efficient and sustainable operation of a communications device in a wireless communications network.

The present application claims the Paris Convention priority from European patent application number EP22184806.2, filed on 13 July 2022, 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 or impliedly admitted as prior art against the present invention.

Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous 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.

Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types 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 communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) 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. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different consideration may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, 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.

One example of a new service is referred to as Ultra Reliable Low Latency Communications (URLLC) services which, as its name suggests, requires that a data unit or packet be communicated with a high reliability and with a low communications delay. Another example of a new service is extended Reality (XR), which may be provided by various user equipment such as wearable devices. XR combines real- world and virtual environments, incorporating aspects such as augmented reality (AR), mixed reality (MR), and virtual reality (VR), and thus requires high quality and minimised interaction delay. Services such as URLLC and XR therefore represent a challenging example for both LTE type communications systems and 5G/NR communications systems, as well as future generation communications systems.

New and future services and wireless communications systems are also becoming increasingly focussed on meeting or contributing to sustainability considerations. The increasing use of different types of network infrastructure equipment and terminal devices associated with different traffic profiles, particularly in view of such sustainability considerations, give rise to new challenges for efficiently and sustainably handling communications in wireless communications systems that need to be addressed.

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 a wireless communications network via a wireless radio interface provided by the wireless communications network. The method comprises transmitting signals to and/or receiving signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, determining that one or more conditions to perform a mobility procedure have been satisfied, determining that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, performing the mobility procedure from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

Embodiments of the present technique, which, in addition to methods of operating communications devices, relate to methods of operating infrastructure equipment, communications devices and infrastructure equipment, circuitry for communications devices and infrastructure equipment, computer programs, and computer-readable storage mediums, can allow for more sustainable and efficient use of radio resources by a communications device operating in a wireless communications network.

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 schematically represents aspects of a conventional handover procedure;

Figure 5 shows an example scenario in which a UE is located at the edge of a cell of its home operator and located at the centre of a cell of another operator;

Figure 6 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique; and

Figure 7 shows a flow diagram illustrating a process of communications in a communications system 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.

Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink. Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink. 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)

Systems incorporating NR technology are expected to support different services (or types of services), which may be characterised by different requirements for latency, data rate and/or reliability. For example, Enhanced Mobile Broadband (eMBB) services are characterised by high capacity with a requirement to support up to 20 Gb/s. The requirements for Ultra Reliable and Low Latency Communications (URLLC) services are for one transmission of a 32 byte packet to be transmitted from the radio protocol layer 2/3 SDU ingress point to the radio protocol layer 2/3 SDU egress point of the radio interface within 1 ms with a reliability of 1 - 10"⁵ (99.999 %) or higher (99.9999%) [2],

Massive Machine Type Communications (mMTC) is another example of a service which may be supported by NR-based communications networks. In addition, systems may be expected to support further enhancements related to Industrial Internet of Things (IIoT) in order to support services with new requirements of high availability, high reliability, low latency, and in some cases, high-accuracy positioning.

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 as 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. The Fl interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, 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.

A detailed illustration of a wireless communications network in which a handover (HO) may be performed is shown in Figure 4. As will be appreciated from Figure 4, a communications device 72 is handed over from a source infrastructure equipment 74 to a target infrastructure equipment 76 forming part of a radio access network to a core network 60. As will be appreciated the communications device 72 is an example of a communications device such as the communications device 14 of Figures 1, 2 and 3. The communications device 72 may be a UE in one example.

Before the handover, the communications device 72 transmits signals on an uplink UL and receive signals on a downlink DL from a source infrastructure equipment 74. The source infrastructure equipment 74 and the target infrastructure equipment 76 may each be thought of as a gNB 1 as shown in Figure 1 or a combination of a controlling node 40 and TRP 10 as shown in Figures 2 and 3. Before the handover, the communications device 72 is shown to transmit uplink data to the source infrastructure equipment 74 via uplink resources UL of a wireless access interface as illustrated generally by dashed arrow 64b to the source infrastructure equipment 74. The communications device 72 may similarly be configured to receive downlink data transmitted by the source infrastructure equipment 74 via downlink resources DL as indicated by dashed arrow 66b from the source infrastructure equipment 74 to the communications device 72. After the handover, the communications device 72 is shown to transmit uplink data to the target infrastructure equipment 76 via uplink resources UL of a wireless access interface as illustrated generally by solid arrow 66a to the target infrastructure equipment 76. The communications device 72 may similarly be configured to receive downlink data transmitted by the target infrastructure equipment 76 via downlink resources DL as indicated by solid arrow 64a from the target infrastructure equipment 76 to the communications device 72.

In Figure 4, the source and target infrastructure equipment 74, 76 are each connected to a core network 60 via interfaces 61, 62 to a controller 74c, 76c of the respective infrastructure equipment 74 and 76. The source and target infrastructure equipment 74, 76 each include a receiver 74b, 76b connected to an antenna 74d, 76d and a transmitter 74a, 76a connected to the antenna 74d, 76d. Correspondingly, the communications device 72 includes a controller 72c connected to a receiver 72b which receives signals from an antenna 72d and a transmitter 72a also connected to the antenna 72d.

The controllers 74c, 76c are configured to control the source and target infrastructure equipment 74, 76 respectively and may comprise processor circuitry which may in turn comprise various sub-units / subcircuits for providing functionality as explained further herein. These sub-units may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Thus the controllers 74c, 76c may comprise circuitry which is suitably configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. The transmitters 74a, 76a and the receivers 74b, 76b may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitters 74a, 76a the receivers 74b, 76b and the controllers 74c, 76c are schematically shown in Figure 4 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 74 will in general comprise various other elements associated with its operating functionality.

Correspondingly, the controller 72c of the communications device 72 is configured to control the transmitter 72a and the receiver 72b and may comprise processor circuitry which may in turn comprise various sub-units / sub-circuits for providing functionality as explained further herein. These sub-units may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Thus the controller 72c may comprise circuitry which is suitably configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. Likewise, the transmitter 72a and the receiver 72b may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitters 72a, receivers 72b, and controllers 72c are schematically shown in Figure 4 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 communications device 72 will in general comprise various other elements associated with its operating functionality, for example a power source, user interface, and so forth, but these are not shown in Figure 4 in the interests of simplicity.

The controllers 74c, 72c may be 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.

Random Access Procedure

In wireless telecommunications networks, such as LTE and NR type networks, there are different Radio Resource Control (RRC) modes for terminal devices. For example, it is common to support an RRC idle mode (RRC IDLE) and an RRC connected mode (RRC CONNECTED). A terminal device in the idle mode may transition to connected mode, for example because it needs to transmit uplink data or respond to a paging request, by undertaking a random access procedure. The random access procedure involves the terminal device transmitting a preamble on a physical random access channel and so the procedure is commonly referred to as a RACH or PRACH procedure / process. As those skilled in the art would understand, typical RACH procedures may comprise either four steps (which are referred to as msgl, msg2, msg3, and msg4) or two steps (which are referred to as msgA and msgB).

6G Wireless Communications and Sustainability in Telecommunications

As described above, several generations of mobile communications have been standardised globally up to now, where each generation took approximately a decade from introduction before the development and introduction of another new generation. For example, generations of mobile communications have moved from the Global System for Mobile Communications (GSM) (2G) to Wideband Code Division Multiple Access (WCDMA) (3G), from WCDMA (3G) to LTE (4G), and most recently from LTE (4G) to NR (5G).

The latest generation of mobile communications is 5G, as discussed above with reference to the example configurations of Figures 2 and 3, where a significant number of additional features have been incorporated in different releases to provide new services and capabilities. Such services include eMBB, IIoT and URLLC as discussed above, but also include such services as 2-step Random Access (RACH), Unlicensed NR (NR-U), Cross-link Interference (CLI) handling for Time Division Duplexing (TDD), Positioning, Small Data Transmissions (SDT), Multicast and Broadcast Services (MBS), Reduced Capability UEs, Vehicular Communications (V2X), Integrated Access and Backhaul (IAB), UE power saving, Non Terrestrial Networks (NTN), NR operation up to 71 GHz, loT over NTN, Non-public networks (NPN), and Radio Access Network (RAN) slicing.

Nevertheless, as in every decade, a new generation (e.g. 6G) is expected to be developed and deployed in the near future (around the year 2030), and will be expected to provide new services and capabilities that the current 5G cannot provide.

One of the areas for investigation for future mobile communications networks is uplink (UL) scheduling enhancements, which are expected to be required due to the increased number of services that require low latency communications and high reliability, as well as high throughput UL data transmissions from the terminal, like tactile internet, Audio-Video field production, and extended Reality (XR). In essence, it is proposed that a mobile terminal should be able to schedule unrestricted UL resources immediately after data arrives in its buffer for transmission, while taking into account the link adaptation parameters so that the transmissions are mostly ensured to be successful. Doing so would allow such mobile terminals to operate not only more efficiently, but also in a more sustainable manner, with less power being wasted.

Sustainability is an increasingly important topic for 6G, and mobile network operators, network vendors, and mobile phone/other user equipment manufacturers are increasingly focussing on their carbon footprint. Seventeen goals for sustainable development have been identified by the United Nations [3], which are:

• No poverty;

• Zero hunger;

• Good health and well-being;

• Quality education;

• Gender equality;

• Clean water and sanitation;

• Affordable and clean energy;

• Decent work and economic growth;

• Industry, innovation, and infrastructure;

• Reduced inequalities;

• Sustainable cities and communities;

• Responsible consumption and production;

• Climate action;

• Life below water;

• Life on land;

• Peace, justice, and strong institutions; and

• Partnerships for the goals.

There are a few use cases of mobile networks which are already known and are helping achieve some of these sustainability targets. For example, such sustainability targets being addressed by mobile networks may include no poverty (by raising awareness), zero hunger (through smart agriculture), good health (mobile health), quality education (remote and immersive learning), clean water and sanitation (smart cities), and industry innovation (services such as URLLC). However, the role of mobile networks in helping achieve some others of the above listed sustainability targets - such as affordable and clean energy, sustainable cities and communities, climate action, and life on Earth - are more questionable.

Mobile networks consume a considerable amount of energy in terms of their worldwide deployment. RAN networks particularly are the leaders in terms of energy consumption in current (i.e. mainly 4G) mobile network deployments. This is due to the deployment of all of the RAN equipment (such as base stations) in the field, as opposed to the more centralised deployment of core network apparatus. At the same time, mobile networks are handling higher and higher amounts of data generated by an ever- increasing number of data hungry users, and hence the overall data usage is growing every month. With new radio access technologies like 5G and 6G, new services and use-cases requiring always-on data applications such as digital twin, XR, gaming, and the metaverse are proposed. Another development for 5G and beyond is that the spectrum used for the communication of data is a higher frequency spectrum (e.g., higher frequencies than used for previous generations of wireless communications networks), resulting in smaller cell sizes. All of these factors contribute to the necessary deployment of a greater amount of RAN equipment in order to meet ever increasing data and coverage/capacity requirements. These requirements go against the above-mentioned sustainability targets described in [3], and thus present a challenge for wireless network operators, network vendors, and mobile phone manufacturers in the overall effort to achieve these sustainability goals.

Figure 5 shows an example scenario in which a UE 85 is a customer of operator A, and is located at the cell edge of one of operator A’s cells 81 which is controlled by gNB 82. At the same time, the UE 85 is located at the centre of a cell 83 of operator B which is controlled by gNB 84, which overlaps with the cell 81 of operator A. From a purely energy-saving point of view, it may be said that the UE 85 simply should connect to operator B’s network rather than that of its own home operator (i.e. operator A); so as to reduce the required transmission power, and to improve throughput and energy efficiency. Figure 5 therefore shows an example of a scenario in which national roaming techniques would be beneficial purely from an energy-saving and sustainability point of view.

However, while national roaming is certainly technically possible, it is not allowed in current networks, due to different operators having different regulations, and so mobility from one operator to another operator within the same country is not supported. Instead, intra-operator handover (such as in the example of Figure 4) is all that a UE is allowed to do. Furthermore, while known and supported international roaming techniques are generally performed as a result of a UE being unable to find its home public land mobile network (PLMN), the UE 85 in the example scenario of Figure 5 is instead in a position where it would be more efficient to connect to operator B’s cell 83 rather than the cell 81 of its home PLMN (i.e. operator A). That is, such a national roaming scenario cannot be said to correspond to international roaming as it would not be performed under the same conditions; i.e. as a result of a UE being unable to find its home PLMN.

As a result of the inability of the UE 85 to switch to operator B’s cell 83 in the example of Figure 5, the uplink transmission power required to be used by the UEs that are at the cell edge of operator A’s cell 81 (such as UE 85) would be increased, even though there is technically a better cell 83 (i.e. in terms of required transmission power) to choose from operator B. This is not favourable, especially when it is necessary to take the sustainability of the wireless network into consideration.

Embodiments of the present technique therefore seek to provide solutions to address such issues of efficiency and sustainability in wireless communications networks.

Sustainable Roaming in Wireless Communications Networks

Figure 6 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device 101, a first infrastructure equipment 102, and a second infrastructure equipment 103, in accordance with at least some embodiments of the present technique. The communications device 101 is configured to (initially) transmit signals to and/or receive signals from a first wireless communications network (of which the first infrastructure equipment 102 may form part) for example, to and from the first infrastructure equipment 102. Furthermore - later - the communications device 101 may be configured to transmit signals to and/or receive signals from a second wireless communications network (of which the second infrastructure equipment 103 may form part), for example, to and from the second infrastructure equipment 103. Specifically, the communications device 101 may be configured to transmit data to and/or receive data from the first and/or second wireless communications networks (e.g. to/from the first and second infrastructure equipment 102, 103) via wireless radio interfaces provided by the first and second wireless communications networks (e.g. the Uu interfaces between the communications device 101 and the Radio Access Networks (RANs), of the first and second wireless communications networks which respectively include the first and second infrastructure equipment 102, 103). The communications device 101 and the first and second infrastructure equipment 102, 103 each comprise a transceiver (or transceiver circuitry) 101.1, 102.1, 103.1, and a controller (or controller circuitry) 101.2, 102.2, 103.2. Each of the controllers 101.2, 102.2, 103.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

As shown in the example of Figure 6, the transceiver circuitry 101.1 and the controller circuitry 101.2 of the communications device 101 are configured in combination to transmit 103 signals to and/or to receive signals from the first wireless communications network (e.g. to/from the first infrastructure equipment 102), whilst the communications device 101 is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, to determine 104 that one or more conditions to perform a mobility procedure have been satisfied, to determine 105 that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network, to perform 106 the mobility procedure from the first wireless communications network to the second wireless communications network, and to transmit 107 signals to and/or to receive signals from the second wireless communications network (e.g. to/from the second infrastructure equipment 103), whilst the communications device 101 is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

Here, the first wireless communications network and the second wireless communications network may be controlled by different network operators, and/or the signals transmitted to and/or received from the first wireless communications network may be transmitted and/or received within a first frequency band while the signals transmitted to and/or received from the second wireless communications network are transmitted and/or received within a second frequency band, where the first frequency band being different to the second frequency band. The coverage region of the first wireless communications network and the coverage region of the second wireless communications network may here both be within a predefined geographic area which may be defined by one or more of a national border, a regional border, or a political border, or may be defined as any other type of geographic area within which the entire area is an area of a single national, regional, or political land. Furthermore, the coverage regions of the first and second wireless communications networks may be defined by respective first and second PLMNs; i.e. the cellular networks of the respective operators of the first and second wireless communications networks in the specific country/region defined by the predetermined geographic area in which the communications device is located.

Essentially, embodiments of the present technique propose novel network configurations and UE behaviour in order to support UE mobility among different operators within a country or other predefined geographic area, in order to optimise the energy efficiency performance of the UE.

The mobility among different operators within a country should be supported in order to improve the energy efficiency performance of the network. And we have different alternatives to support such mobility.

In some arrangements of embodiments of the present technique, the conditions to allow mobility between different mobile network operators are configured by the non-access stratum (NAS) layer. In other words, the communications device may be configured to receive, from the core network (e.g. from an Access and Mobility Function (AMF) or Mobility Management Entity (MME) within the core network), non-access stratum, NAS, signalling comprising an indication of the one or more conditions to perform the mobility procedure. Such conditions to trigger such switch could be: • Link quality; e.g. when a link quality measure, such as reference signal received power (RSRP) or reference signal received quality (RSRQ) or the like, falls below a threshold, and there are no other cells of the same home mobile network operator to choose from, the UE may be allowed to search for and connect to cells of another mobile network operator which have a better link quality. In other words, the one or more conditions to perform the mobility procedure may comprise a quality of signals received from the first wireless communications network falling below a first threshold and/or a quality of signals received from the second wireless communications network exceeding a second threshold (where the first and second thresholds may be the same, or there may be a gap between them, which can be fixed or can be configured by the network(s));

• The distance between the UE and the serving cell (and/or neighbouring cells of the same network operator). Pathloss increases in proportion to the distance between UE and the cell, and so if the UE has knowledge of its own location as well as the location of the serving/neighbouring cell(s), the UE is able to roughly determine the pathloss. The UE may receive assistance information in respect of the serving/neighbour cell locations from the network in advance, allowing it to more easily determine such distances (and pathloss) based on its own location and this received assistance information. In other words, the one or more conditions to perform the mobility procedure may comprise a distance between the communications device and an infrastructure equipment of the first wireless communications network exceeding a first threshold and/or a distance between the communications device and an infrastructure equipment of the second wireless communications network falling below a second threshold (where the first and second thresholds may be the same, or there may be a gap between them, which can be fixed or can be configured by the network(s)); and

• When the UE’s energy efficiency performance (e.g. Joule/bit) is worse than its configured energy efficiency profile, the UE may be allowed to switch to a cell operated by a different network operator to its home PLMN which is able to support energy efficient operation in accordance with the UE’s energy efficiency profile. In other words, the one or more conditions to perform the mobility procedure may comprise an energy efficiency performance of the communications device falling below a defined threshold. Here, this energy efficiency performance of the communications device may define an amount of energy required to transfer a specified portion of data.

In accordance with such arrangements of embodiments of the present technique, energy efficiency performance may be monitored in any of multiple ways, e.g. by the network and/or by the UE.

Where the network monitors energy efficiency performance, the base station may measure both the transmission power for the UE and the power consumption of baseband processing in addition to traffic volume. The base station may then calculate the energy-per-data volume based on that measurement. The base station may then indicate this monitored energy efficiency performance to UE. In other words, the communications device may be configured to receive, from the first wireless communications network, an indication of the energy efficiency performance of the communications device.

Where the UE monitors energy efficiency performance, the UE may measure power consumption in addition to throughput. However, those skilled in the art would appreciate that the UE may not be able to distinguish between the power consumption of applications and that of radio communication. Instead, the UE may, as the measured power consumption, use the transmission power (or power headroom) of the UE and the traffic volume to estimate the power consumption of radio communication in a simplified way. In other words, the communications device may be configured to measure power consumption of the communications device, to measure throughput of the communications device, and to determine the energy efficiency performance of the communications device based on the measured power consumption and the measured throughput. Here, the UE may be configured to report the determined energy efficiency performance to the network.

In some arrangements of embodiments of the present technique, in order to allow the UE to be aware of the existence of the cells that belongs to other operators which it is possible for the UE to switch to, the serving cell may broadcast cell configurations of other operators (or those of the operators that are willing to collaborate with the UE’s home operator). In other words, the communications device may be configured to receive signalling from the first wireless communications network, the signalling comprising an indication of configuration information associated with the second wireless communications network.

In some implementations, this (the cell configurations of other operators) can be implemented in the system information as an on-demand SI. In other words, the communications device may be configured to transmit, to the first wireless communications network, a request for the signalling, wherein the signalling is received from the first wireless communications network in response to the transmitted request.

In various arrangements of embodiments of the present technique, the mobility procedure may be a handover procedure, which comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in connected mode. Alternatively, the mobility procedure may be a cell reselection procedure, which comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in idle mode/Inactive mode.

In some other arrangements of embodiments of the present technique, the network (i.e. via the serving cell of a UE) may - as the mobility procedure - send an RRC connection release message to the UE, where this RRC connection release message includes a redirection message and designates the frequency (which in accordance with such arrangements of embodiments of the present technique may be a frequency band of a different mobile network operator) or designates the different mobile network operator itself for the UE to access. In other words, the communications device may be configured to perform the mobility procedure by receiving, from the first wireless communications network, a connection release message indicating that the communications device is to release a connection between the communications device and the first wireless communications network, wherein the connection release message comprises an indicator that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network. Here, the indicator may explicitly identify the second wireless communications network, and/or the indicator may the indicator identify a second frequency band, the second frequency band being a frequency band within which the communications device is to transmit the signals to and/or receive the signals from the second wireless communications network and being different to a first frequency band within which the signals transmitted to and/or received from the first wireless communications network are transmitted and/or received.

In some arrangements of embodiments of the present technique, the network may detect that a UE is connecting to the network in an energy inefficient manner; which may determined from, for example, the UE’s location (i.e. via a received location report from the UE), and/or the UE’s sustainability profile in the core network, and/or from a measured energy efficiency performance of the UE which may be determined by the network or the UE in a manner as described above. In such a case, the network may include a preferable frequency band for the UE to access (where this preferable frequency band may belong to another operator(s)) in the RRC connection release message.

In some implementations, this indication may be included in the CellReselectionPriority list in the RRC connection release message, in order to instruct the UE to connect to the other network via this frequency band. For example, the network may configure the priority of the inter-operator frequency band as high/medium high in the CellReselectionPriority list (which defines values between 0 and 7, where 0 designates a lowest priority and 7 designates a highest priority). In other words, the indicator may be included within a cell reselection priority list and indicates a priority of the second wireless communications network. This may be triggered by the network when, for example, RSRP at the UE falls below a certain threshold and there are no other cells to choose from the same operator, and/or when the UE is located at the cell edge, and/or when the UE’s energy efficiency performance is not satisfied.

In some other implementations, the frequency band of the other operator may be indicated outside of the CellReselectionPriority list, or may be listed such that the UE treats this frequency band as a highest priority and does not waste power measuring other (lower priority) frequencies listed in the priority list. In other words, the indicator may be included within the connection release message separately to a cell reselection priority list.

In some arrangements of embodiments of the present technique, the network (i.e. via the serving cell of a UE) may configure the frequency priority, e.g. in broadcast SI, according to certain conditions. In other words, the configuration information may comprise an indication of a priority of the second wireless communications network, where here the configuration information may further comprise an indication of one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

For example, in the broadcast SI, the network may configure the priority of the inter-operator frequency as high/medium high in the CellReselectionPriority list, but specifically on the condition that, for example, the link quality for a UE operating in that frequency band should be above a certain threshold. Otherwise, if the link quality for a UE operating in that frequency band is not above the certain threshold, such a high/medium priority for the other network operator - i.e. only those inter-operator frequency cells with a good quality (e.g. above the threshold) will be available for the UE to select. The same may be true of other conditions, such as those related to UE distance from the cell, the UE’s energy efficiency performance or sustainability profile, etc. In other words, the indicator may indicate one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

In other arrangements of embodiments of the present technique, UE may remember its sustainability profile from its previous connection to/communication with the core network, and may therefore indicate this sustainability profile to the network (e.g. in msgl/msg3 when performing a RACH procedure) for a new connection with this network. Here, the sustainability profile may indicate an expected energy efficiency performance associated with the UE, which may be such a performance as the UE is willing or required (if possible) to achieve. This energy efficiency performance may be defined in terms of Joules per bit, or power level, and may indicate the UEs willingness to accept certain levels of energy efficiency at (or in some cases within a specified amount below) that indicated by the sustainability profile.

Likewise, the UE’s sustainability profile may indicate the UE’s readiness to accept certain services with or without a reduced Quality of Service (QoS) and/or Quality of Experience (QoE), provided that doing so (i.e. accepting a certain QoS and/or QoE) will enable the sustainability targets (which may be associated with or defined by the sustainability profile) to be achieved.

The cells of the first and second wireless communications networks may also be associated with sustainability profiles, for example indicating that they support full service delivery for a UE within that cell or a reduced service delivery for a UE in that cell, and this information may be taken into consideration (for example, in combination with the UE’s sustainability profile) when considering whether the UE should perform a mobility procedure such as handover or cell reselection. For example, the resolution of video (e.g. 4K -> HD) and/or refresh rate (e.g. 120 frame per second to 30 frame per second) may be reduced to save radio resources. The sustainability profile (of the UE and/or cells) may be mainly related to sustainability targets such as power consumption. However, such sustainability profiles may not be necessarily related to sustainability targets. For example, the latency of backhaul links may depend on the cell/base station. Latency mainly depends on the type of backhaul link (e.g. optical fiber, mmWave, satellite, and so on), which is connected to the cell/base station. If the latency is high, a UE may determine whether it accepts the reduced service with high latency or whether it gives up the service based on cell sustainability profile (and/or its own sustainability profile).

If the network determines that the UE is experiencing bad radio conditions and thus the sustainability profile of the UE is not satisfied by the UE connecting to the network while experiencing these bad radio conditions, then network can immediately send an RRC reject message to end the RACH procedure, along with redirected carrier information including an indication of the frequency band of a neighbouring (and different mobile network operator) cell/frequency. In other words, the communications device may be configured to receive, from the core network, an indication of a sustainability profile associated with the communications device, and subsequently the communications device may be configured to perform the mobility procedure by transmitting, to the first wireless communications network, an indication of the sustainability profile, and receiving, based on the transmitted indication of the sustainability profile, an indication that the communications device is to perform the mobility procedure from the first wireless communications network to the second wireless communications network. Here, the Random Access Response (RAR) message may comprise the a rejection (along with an indication that the UE should switch to another cell, which may a cell of a different mobile network operator) if the sustainability profile is indicated by the UE’s random access preamble (i.e. msgl), and in some cases where this preamble is transmitted with a high power. Alternatively, the RRC reject message may be transmitted as described above if the sustainability profile is transmitted within msg3. In another alternative implementation, the UE’s sustainability may be transmitted in msg5 or later (i.e. where the RACH procedure has been completed and the UE is connected to the network). In such cases, the network may send an RRC connection release message as described in the previous paragraphs above.

In some such arrangements, RACH resources - which may be used for the indication of the sustainability profile during the RACH procedure as described above - may be reserved for energy efficient (EE) UEs. Here, an EE-UE may be for example a UE with an energy efficiency performance at or above a certain predefined or dynamic/semi-static threshold (where the energy efficiency performance may be determined by the UE or network in the same or a similar manner as described above), and/or an EE-UE may for example be a specific type of UE as defined in the specifications. In other words, the indication of the sustainability profile may be transmitted, within random access control, RACH, resources of the first wireless radio interface, as part of a RACH message, and wherein the RACH resources are reserved for energy efficient communications devices.

In other arrangements of embodiments of the present technique, if the UE is aware of its sustainability profile (e.g. from its previous connection to/communication with the core network) then the UE, during cell selection/reselection, may not select a cell of its home PLMN if such a cell(s) is below a certain threshold, e.g. in terms of quality (RSRP/RSRQ or the like). If system information indicates that selection of another operator cell is allowed, then the UE may select/re select a cell belonging to another operator, provided that this cell does satisfy the radio conditions for cell selection/ reselection (e.g. a quality of reference signals received from the neighbouring cell of the other operator is above a threshold). In other words, the communications device may be configured to determine that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network is based on both of the one or more conditions to perform the mobility procedure being satisfied and the sustainability profile

In other arrangements of embodiments of the present technique, a UE in connected mode may be configured to measure another operator’s cell and a new measurement event may be defined for such purposes, whereby UE reports (to its own serving cell) if a quality of signals received from the other operator’s cell is above a threshold. In other words, the communications device may be configured to perform measurements of reference signals received from the second wireless communications network, and to transmit, to the first wireless communications network if a specified condition is satisfied, an indication of the performed measurements. Here, the specified condition may comprise a quality of the measured reference signals being above a threshold.

In some such arrangements of embodiments of the present technique, another new event could be if the other operator cell’s measurements are above those of the serving cell. These measurements can be modelled as inter-frequency or inter-RAT measurements within current measurement configurations, and the model for performing measurements (of the other operator’s frequency band) may be configured as an inter-frequency measurement object. Here, the UE may be configured to perform measurements such as inter-frequency measurements based on the UE’s capability, e.g. with respect to whether there is a need for measurement gaps or not. Similarly, as an alternative, the other operator’s frequency may be included in inter-RAT measurements. In other words, the specified condition may comprise a quality of the measured reference signals being higher than a quality of measured reference signals received from the first wireless communications network.

In some such arrangements, it may be the case that - so as to achieve agreements between different network operators in the allowance of and network configuration/UE behaviour for national roaming - a certain level of preference is given to a UE’s home PLMN. For example, in respect of the arrangements described above with respect to the new event comparing measured qualities of the serving and other operator’s cells, a UE may be configured to switch to the other operator’s cell (or even simply report the quality of the other operator’s cell) only if the quality of that cell is more than a certain amount (i.e. above a threshold amount more) better than the quality of the serving cell. In other words, the specified condition may comprise a quality of the measured reference signals being more than a specified amount higher than a quality of measured reference signals received from the first wireless communications network.

Energy saving objectives may not be fully achieved for a mobile communications network with respect to a given UE if the optimal path beyond the RAN node communicating with that UE is not likewise specified in accordance with those energy saving objectives. Similarly to international roaming, there are primarily two options for data transfer in national roaming scenarios:

Data is offloaded in visited PLMN; or

Data is routed back to home PLMN and then offloaded to intemet/application. In other words, in accordance with embodiments of the present technique, in the first of the above options, the second (i.e. other operator’s) wireless communications network (e.g. via the infrastructure equipment controlling the cell of that network) may be configured to receive data from the communications device after the mobility procedure has been performed, and to transmit, to the core network, the data received from the communications device.

In the second of the above options, in accordance with embodiments of the present technique, the first (i.e. home PLMN’s) wireless communications network (e.g. via the infrastructure equipment controlling the cell of that network) may be configured to receive, from the second wireless communications network after the mobility procedure has been performed, data transmitted by the communications device to the second wireless communications network, and to transmit, to a core network, the received data.

In respect of this second option, in terms of international roaming, this would typically involve a longer path for the offloading of data, due to country boundaries and the need to go through international gateways. However, in respect of national roaming, this may not always be true as the data does not need to go through an international gateway, and the cells of the different network operators may also be very closely located in a geographical sense. For example, it may make more sense for data from a user of a first PLMN connected to a cell of a different PLMN and located near to the HQ location of that different PLMN to be offloaded to the core network by that different PLMN to which the user’s UE is connected rather than traffic being routed back to its home (first) PLMN. In this regard, and in accordance with arrangements of embodiments of the present technique, there are three options:

• Traffic rules may be handled like roaming as described above. Here, the core network may be common to the first wireless communications network and the second wireless communications network;

• RAN nodes may be interconnected to different operator core networks (where data can be sent to any of these different core networks based on the operator’s cell the UE is connected to) in a similar manner to RAN sharing. Here, sharing may work only for selected UEs based on their sustainability profile and/or currently experienced radio conditions of those UEs (i.e. UEs whose sustainability profile is not currently met or which are experiencing bad radio conditions may be allowed to take part in such RAN sharing, where such permissions/conditions may be configured individually for each UE via dedicated signalling). In other words, the core network and the second wireless communications network may both be controlled by a second network operator, the second network operator being different to a first network operator controlling the first wireless communications network. Here, the infrastructure equipment may transmit signals to and/or receive signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network. Furthermore, here, the infrastructure equipment may transmit signals to and/or receive signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network dependent on one or both of a quality of signals transmitted between the communications device and the infrastructure equipment and a sustainability profile associated with the communications device; and

• Operator packet gateways (P-GWs) or Data network may be interconnected for offloading traffic for a home UE and initiated from another operator’s network. In other words, the data may be transmitted to a packet gateway of the core network, wherein the packet gateway is common to the first wireless communications network and the second wireless communications network. This data network may be used for offering sustainable services. Figure 7 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 7 is a method of operating a communications device.

The method begins in step S 1. The method comprises, in step S2, transmitting signals to and/or receiving signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network. In step S3, the process comprises determining that one or more conditions to perform a mobility procedure have been satisfied. In step S4, the method comprises determining that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network. Then, in step S5, the process comprises performing the mobility procedure from the first wireless communications network to the second wireless communications network. Following this, in step S6, the method comprises transmitting signals to and/or receiving signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network. The process ends in step S7.

Those skilled in the art would appreciate that the method shown by Figure 7 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in this method, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications system shown in Figure 6, it would be clear to those skilled in the art that they could be equally applied to other systems to those described herein.

Those skilled in the art would further appreciate that such infrastructure equipment 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 infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure. As those skilled in the art would appreciate, although embodiments of the present technique have been described largely in view of 5G/6G technologies, such embodiments of the present technique may apply similarly to macro cells of 2G, 3G, 4G, and 5G as they do to 6G, and more broadly, to these radio access technologies.

The following numbered paragraphs provide further example aspects and features of the present technique:

Paragraph 1. A method of operating a communications device, the method comprising transmitting signals to and/or receiving signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, determining that one or more conditions to perform a mobility procedure have been satisfied, determining that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, performing the mobility procedure from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

Paragraph 2. A method according to Paragraph 1, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators.

Paragraph 3. A method according to Paragraph 1 or Paragraph 2, wherein the signals transmitted to and/or received from the first wireless communications network are transmitted and/or received within a first frequency band, and the signals transmitted to and/or received from the second wireless communications network are transmitted and/or received within a second frequency band, the first frequency band being different to the second frequency band.

Paragraph 4. A method according to any of Paragraphs 1 to 3, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

Paragraph 5. A method according to Paragraph 4, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

Paragraph 6. A method according to any of Paragraphs 1 to 5, comprising receiving, from a core network, non-access stratum, NAS, signalling comprising an indication of the one or more conditions to perform the mobility procedure.

Paragraph 7. A method according to Paragraph 6, wherein the one or more conditions to perform the mobility procedure comprise a quality of signals received from the first wireless communications network falling below a first threshold and/or a quality of signals received from the second wireless communications network exceeding a second threshold.

Paragraph 8. A method according to Paragraph 6 or Paragraph 7, wherein the one or more conditions to perform the mobility procedure comprise a distance between the communications device and an infrastructure equipment of the first wireless communications network exceeding a first threshold and/or a distance between the communications device and an infrastructure equipment of the second wireless communications network falling below a second threshold.

Paragraph 9. A method according to any of Paragraphs 6 to 8, wherein the one or more conditions to perform the mobility procedure comprise an energy efficiency performance of the communications device falling below a defined threshold. Paragraph 10. A method according to Paragraph 9, wherein the energy efficiency performance of the communications device defines an amount of energy required to transfer a specified portion of data. Paragraph 11. A method according to Paragraph 9 or Paragraph 10, comprising receiving, from the first wireless communications network, an indication of the energy efficiency performance of the communications device.

Paragraph 12. A method according to any of Paragraphs 9 to 11, comprising measuring power consumption of the communications device, measuring throughput of the communications device, and determining the energy efficiency performance of the communications device based on the measured power consumption and the measured throughput.

Paragraph 13. A method according to any of Paragraphs 1 to 12, comprising receiving signalling from the first wireless communications network, the signalling comprising an indication of configuration information associated with the second wireless communications network.

Paragraph 14. A method according to Paragraph 13, comprising transmitting, to the first wireless communications network, a request for the signalling, wherein the signalling is received from the first wireless communications network in response to the transmitted request.

Paragraph 15. A method according to Paragraph 13 or Paragraph 14, wherein the configuration information comprises an indication of a priority of the second wireless communications network. Paragraph 16. A method according to any of Paragraphs 13 to 15, wherein the configuration information comprises an indication of one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

Paragraph 17. A method according to any of Paragraphs 1 to 16, wherein the mobility procedure is a handover procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in connected mode.

Paragraph 18. A method according to any of Paragraphs 1 to 17, wherein the mobility procedure is a cell reselection procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in idle mode or inactive mode.

Paragraph 19. A method according to any of Paragraphs 1 to 18, wherein the performing the mobility procedure comprises receiving, from the first wireless communications network, a connection release message indicating that the communications device is to release a connection between the communications device and the first wireless communications network, wherein the connection release message comprises an indicator that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network.

Paragraph 20. A method according to Paragraph 19, wherein the indicator explicitly identifies the second wireless communications network.

Paragraph 21. A method according to Paragraph 19 or Paragraph 20, wherein the indicator identifies a second frequency band, the second frequency band being a frequency band within which the communications device is to transmit the signals to and/or receive the signals from the second wireless communications network and being different to a first frequency band within which the signals transmitted to and/or received from the first wireless communications network are transmitted and/or received. Paragraph 22. A method according to any of Paragraphs 19 to 21, wherein the indicator is included within a cell reselection priority list and indicates a priority of the second wireless communications network.

Paragraph 23. A method according to any of Paragraphs 19 to 22, wherein the indicator is included within the connection release message separately to a cell reselection priority list.

Paragraph 24. A method according to any of Paragraphs 19 to 23, wherein the indicator indicates one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

Paragraph 25. A method according to any of Paragraphs 1 to 24, comprising receiving, from a core network, an indication of a sustainability profile associated with the communications device.

Paragraph 26. A method according to Paragraph 25, wherein the performing the mobility procedure comprises transmitting, to the first wireless communications network, an indication of the sustainability profile, and receiving, based on the transmitted indication of the sustainability profile, an indication that the communications device is to perform the mobility procedure from the first wireless communications network to the second wireless communications network.

Paragraph 27. A method according to Paragraph 26, wherein the indication of the sustainability profile is transmitted, within random access control, RACH, resources of the first wireless radio interface, as part of a RACH message, and wherein the RACH resources are reserved for energy efficient communications devices.

Paragraph 28. A method according to any of Paragraphs 25 to 27, wherein the determining that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network is based on both of the one or more conditions to perform the mobility procedure being satisfied and the sustainability profile.

Paragraph 29. A method according to any of Paragraphs 1 to 28, comprising performing measurements of reference signals received from the second wireless communications network, and transmitting, to the first wireless communications network if a specified condition is satisfied, an indication of the performed measurements.

Paragraph 30. A method according to Paragraph 29, wherein the specified condition comprises a quality of the measured reference signals being above a threshold.

Paragraph 31. A method according to Paragraph 29 or Paragraph 30, wherein the specified condition comprises a quality of the measured reference signals being higher than a quality of measured reference signals received from the first wireless communications network.

Paragraph 32. A method according to any of Paragraphs 29 to 31, wherein the specified condition comprises a quality of the measured reference signals being more than a specified amount higher than a quality of measured reference signals received from the first wireless communications network.

Paragraph 33. A communications device comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, to determine that one or more conditions to perform a mobility procedure have been satisfied, to determine that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, to perform the mobility procedure from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network. Paragraph 34. Circuitry for a communications device comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, to determine that one or more conditions to perform a mobility procedure have been satisfied, to determine that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, to perform the mobility procedure from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network. Paragraph 35. A method of operating an infrastructure equipment forming part of a first wireless communications network, the method comprising transmitting signals to and/or receiving signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, performing a mobility procedure with the communications device, and determining that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network. Paragraph 36. A method according to Paragraph 35, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators. Paragraph 37. A method according to Paragraph 35 or Paragraph 36, wherein the signals transmitted to and/or received from the communications device are transmitted and/or received within a first frequency band, the first frequency band being different to a second frequency band in which the communications device is to transmit signals to and/or receive signals from the second wireless communications network after the mobility procedure has been performed.

Paragraph 38. A method according to any of Paragraphs 35 to 37, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

Paragraph 39. A method according to Paragraph 38, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

Paragraph 40. A method according to any of Paragraphs 35 to 39, comprising transmitting, to the communications device, an indication of an energy efficiency performance of the communications device, wherein the energy efficiency performance of the communications device defines an amount of energy required to transfer a specified portion of data.

Paragraph 41. A method according to any of Paragraphs 35 to 40, comprising transmitting signalling to the communications device, the signalling comprising an indication of configuration information associated with the second wireless communications network.

Paragraph 42. A method according to Paragraph 41, comprising receiving, from the communications device, a request for the signalling, and transmitting the signalling to the communications device in response to the received request.

Paragraph 43. A method according to Paragraph 41 or Paragraph 42, wherein the configuration information comprises an indication of a priority of the second wireless communications network. Paragraph 44. A method according to any of Paragraphs 41 to 43, wherein the configuration information comprises an indication of one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

Paragraph 45. A method according to any of Paragraphs 35 to 44, wherein the mobility procedure is a handover procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in connected mode.

Paragraph 46. A method according to any of Paragraphs 35 to 45, wherein the mobility procedure is a cell reselection procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in idle mode or inactive mode.

Paragraph 47. A method according to any of Paragraphs 35 to 46, wherein the performing the mobility procedure comprises transmitting, to the communications device, a connection release message indicating that the communications device is to release a connection between the communications device and the infrastructure equipment, wherein the connection release message comprises an indicator that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network.

Paragraph 48. A method according to Paragraph 47, wherein the indicator explicitly identifies the second wireless communications network.

Paragraph 49. A method according to Paragraph 47 or Paragraph 48, wherein the indicator identifies a second frequency band, the second frequency band being a frequency band within which the communications device is to transmit the signals to and/or receive the signals from the second wireless communications network and being different to a first frequency band within which the signals transmitted to and/or received from the infrastructure equipment are transmitted and/or received. Paragraph 50. A method according to any of Paragraphs 47 to 49, wherein the indicator is included within a cell reselection priority list and indicates a priority of the second wireless communications network.

Paragraph 51. A method according to any of Paragraphs 47 to 50, wherein the indicator is included within the connection release message separately to a cell reselection priority list.

Paragraph 52. A method according to any of Paragraphs 47 to 51, wherein the indicator indicates one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

Paragraph 53. A method according to any of Paragraphs 35 to 52, wherein the performing the mobility procedure comprises receiving, from the communications device, an indication of a sustainability profile associated with the communications device, and transmitting, based on the received indication of the sustainability profile, an indication that the communications device is to perform the mobility procedure from the first wireless communications network to the second wireless communications network.

Paragraph 54. A method according to Paragraph 53, wherein the indication of the sustainability profile is received, within random access control, RACH, resources of the wireless radio interface, as part of a RACH message, and wherein the RACH resources are reserved for energy efficient communications devices.

Paragraph 55. A method according to any of Paragraphs 35 to 53, comprising receiving, from the communications device if a specified condition is satisfied, an indication of measured reference signals received by the communications device from the second wireless communications network.

Paragraph 56. A method according to Paragraph 55, wherein the specified condition comprises a quality of the measured reference signals being above a threshold.

Paragraph 57. A method according to Paragraph 55 or Paragraph 56, wherein the specified condition comprises a quality of the measured reference signals being higher than a quality of measured reference signals received from the infrastructure equipment.

Paragraph 58. A method according to any of Paragraphs 55 to 57, wherein the specified condition comprises a quality of the measured reference signals being more than a specified amount higher than a quality of measured reference signals received from the infrastructure equipment.

Paragraph 59. A method according to any of Paragraphs 35 to 58, comprising receiving, from the second wireless communications network after the mobility procedure has been performed, data transmitted by the communications device to the second wireless communications network, and transmitting, to a core network, the received data.

Paragraph 60. An infrastructure equipment forming part of a first wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, to perform a mobility procedure with the communications device, and to determine that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network. Paragraph 61. Circuitry for an infrastructure equipment forming part of a first wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, to perform a mobility procedure with the communications device, and to determine that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network. Paragraph 62. A method of operating an infrastructure equipment forming part of a second wireless communications network, the method comprising performing a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

Paragraph 63. A method according to Paragraph 62, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators.

Paragraph 64. A method according to Paragraph 62 or Paragraph 63, wherein the signals transmitted to and/or received from the communications device are transmitted and/or received within a second frequency band, the second frequency band being different to a first frequency band in which the communications device is to transmit signals to and/or receive signals from the first wireless communications network before the mobility procedure has been performed.

Paragraph 65. A method according to any of Paragraphs 62 to 64, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

Paragraph 66. A method according to Paragraph 65, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

Paragraph 67. A method according to any of Paragraphs 62 to 66, comprising receiving data from the communications device after the mobility procedure has been performed, and transmitting, to a core network, the data received from the communications device.

Paragraph 68. A method according to Paragraph 67, wherein the core network is common to the first wireless communications network and the second wireless communications network.

Paragraph 69. A method according to Paragraph 67 or Paragraph 68, wherein the data is transmitted to a packet gateway of the core network, wherein the packet gateway is common to the first wireless communications network and the second wireless communications network.

Paragraph 70. A method according to any of Paragraphs 67 to 69, wherein the core network and the second wireless communications network are both controlled by a second network operator, the second network operator being different to a first network operator controlling the first wireless communications network.

Paragraph 71. A method according to Paragraph 70, wherein the infrastructure equipment transmits signals to and/or receives signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network. Paragraph 72. A method according to Paragraph 71, wherein the infrastructure equipment transmits signals to and/or receives signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network dependent on one or both of a quality of signals transmitted between the communications device and the infrastructure equipment and a sustainability profile associated with the communications device.

Paragraph 73. A method according to any of Paragraphs 62 to 72, comprising receiving data from the communications device after the mobility procedure has been performed, and transmitting, to the first wireless communications network, the data received from the communications device for forwarding, by the first wireless communications network, to a core network. Paragraph 74. An infrastructure equipment forming part of a second wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to perform a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

Paragraph 75. Circuitry for an infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to perform a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

Paragraph 76. A wireless communications system comprising a communications device according to Paragraph 33 and at least one of an infrastructure equipment according to Paragraph 60 and an infrastructure equipment according to Paragraph 74.

Paragraph 77. 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 32, Paragraphs 35 to 59, or Paragraphs 62 to 73.

Paragraph 78. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 77.

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] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3rd Generation Partnership Project, vl4.3.0, August 2017.

[3] United Nations, “Sustainable Development Goals”, [Online], Available at: https://sdgs.un.org/goals.

Claims

CLAIMS What is claimed is:

1. A method of operating a communications device, the method comprising transmitting signals to and/or receiving signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, determining that one or more conditions to perform a mobility procedure have been satisfied, determining that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, performing the mobility procedure from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

2. A method according to Claim 1, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators.

3. A method according to Claim 1, wherein the signals transmitted to and/or received from the first wireless communications network are transmitted and/or received within a first frequency band, and the signals transmitted to and/or received from the second wireless communications network are transmitted and/or received within a second frequency band, the first frequency band being different to the second frequency band.

4. A method according to Claim 1, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

5. A method according to Claim 4, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

6. A method according to Claim 1, comprising receiving, from a core network, non-access stratum, NAS, signalling comprising an indication of the one or more conditions to perform the mobility procedure.

7. A method according to Claim 6, wherein the one or more conditions to perform the mobility procedure comprise a quality of signals received from the first wireless communications network falling below a first threshold and/or a quality of signals received from the second wireless communications network exceeding a second threshold.

8. A method according to Claim 6, wherein the one or more conditions to perform the mobility procedure comprise a distance between the communications device and an infrastructure equipment of the first wireless communications network exceeding a first threshold and/or a distance between the communications device and an infrastructure equipment of the second wireless communications network falling below a second threshold.

9. A method according to Claim 6, wherein the one or more conditions to perform the mobility procedure comprise an energy efficiency performance of the communications device falling below a defined threshold.

10. A method according to Claim 9, wherein the energy efficiency performance of the communications device defines an amount of energy required to transfer a specified portion of data.

11. A method according to Claim 9, comprising receiving, from the first wireless communications network, an indication of the energy efficiency performance of the communications device.

12. A method according to Claim 9, comprising measuring power consumption of the communications device, measuring throughput of the communications device, and determining the energy efficiency performance of the communications device based on the measured power consumption and the measured throughput.

13. A method according to Claim 1, comprising receiving signalling from the first wireless communications network, the signalling comprising an indication of configuration information associated with the second wireless communications network.

14. A method according to Claim 13, comprising transmitting, to the first wireless communications network, a request for the signalling, wherein the signalling is received from the first wireless communications network in response to the transmitted request.

15. A method according to Claim 13, wherein the configuration information comprises an indication of a priority of the second wireless communications network.

16. A method according to Claim 13, wherein the configuration information comprises an indication of one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

17. A method according to Claim 1, wherein the mobility procedure is a handover procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in connected mode.

18. A method according to Claim 1, wherein the mobility procedure is a cell reselection procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in idle mode or inactive mode.

19. A method according to Claim 1, wherein the performing the mobility procedure comprises receiving, from the first wireless communications network, a connection release message indicating that the communications device is to release a connection between the communications device and the first wireless communications network, wherein the connection release message comprises an indicator that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network.

20. A method according to Claim 19, wherein the indicator explicitly identifies the second wireless communications network.

21. A method according to Claim 19, wherein the indicator identifies a second frequency band, the second frequency band being a frequency band within which the communications device is to transmit the signals to and/or receive the signals from the second wireless communications network and being different to a first frequency band within which the signals transmitted to and/or received from the first wireless communications network are transmitted and/or received.

22. A method according to Claim 19, wherein the indicator is included within a cell reselection priority list and indicates a priority of the second wireless communications network.

23. A method according to Claim 19, wherein the indicator is included within the connection release message separately to a cell reselection priority list.

24. A method according to Claim 19, wherein the indicator indicates one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

25. A method according to Claim 1, comprising receiving, from a core network, an indication of a sustainability profile associated with the communications device.

26. A method according to Claim 25, wherein the performing the mobility procedure comprises transmitting, to the first wireless communications network, an indication of the sustainability profile, and receiving, based on the transmitted indication of the sustainability profile, an indication that the communications device is to perform the mobility procedure from the first wireless communications network to the second wireless communications network.

27. A method according to Claim 26, wherein the indication of the sustainability profile is transmitted, within random access control, RACH, resources of the first wireless radio interface, as part of a RACH message, and wherein the RACH resources are reserved for energy efficient communications devices.

28. A method according to Claim 25, wherein the determining that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network is based on both of the one or more conditions to perform the mobility procedure being satisfied and the sustainability profile.

29. A method according to Claim 1, comprising performing measurements of reference signals received from the second wireless communications network, and transmitting, to the first wireless communications network if a specified condition is satisfied, an indication of the performed measurements.

30. A method according to Claim 29, wherein the specified condition comprises a quality of the measured reference signals being above a threshold.

31. A method according to Claim 29, wherein the specified condition comprises a quality of the measured reference signals being higher than a quality of measured reference signals received from the first wireless communications network.

32. A method according to Claim 29, wherein the specified condition comprises a quality of the measured reference signals being more than a specified amount higher than a quality of measured reference signals received from the first wireless communications network.

33. A communications device comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, to determine that one or more conditions to perform a mobility procedure have been satisfied, to determine that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, to perform the mobility procedure from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

34. Circuitry for a communications device comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a first wireless communications network, whilst the communications device is located within a coverage region of the first wireless communications network, via a first wireless radio interface provided by the first wireless communications network, to determine that one or more conditions to perform a mobility procedure have been satisfied, to determine that the mobility procedure comprises switching from the first wireless communications network to a second wireless communications network, to perform the mobility procedure from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the second wireless communications network, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a second wireless radio interface provided by the second wireless communications network.

35. A method of operating an infrastructure equipment forming part of a first wireless communications network, the method comprising transmitting signals to and/or receiving signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, performing a mobility procedure with the communications device, and determining that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network.

36. A method according to Claim 35, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators.

37. A method according to Claim 35, wherein the signals transmitted to and/or received from the communications device are transmitted and/or received within a first frequency band, the first frequency band being different to a second frequency band in which the communications device is to transmit signals to and/or receive signals from the second wireless communications network after the mobility procedure has been performed.

38. A method according to Claim 35, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

39. A method according to Claim 38, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

40. A method according to Claim 35, comprising transmitting, to the communications device, an indication of an energy efficiency performance of the communications device, wherein the energy efficiency performance of the communications device defines an amount of energy required to transfer a specified portion of data.

41. A method according to Claim 35, comprising transmitting signalling to the communications device, the signalling comprising an indication of configuration information associated with the second wireless communications network.

42. A method according to Claim 41, comprising receiving, from the communications device, a request for the signalling, and transmitting the signalling to the communications device in response to the received request.

43. A method according to Claim 41, wherein the configuration information comprises an indication of a priority of the second wireless communications network.

44. A method according to Claim 41, wherein the configuration information comprises an indication of one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

45. A method according to Claim 35, wherein the mobility procedure is a handover procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in connected mode.

46. A method according to Claim 35, wherein the mobility procedure is a cell reselection procedure, and comprises the communications device switching from the first wireless communications network to a second wireless communications network while the communications device is operating in idle mode or inactive mode.

47. A method according to Claim 35, wherein the performing the mobility procedure comprises transmitting, to the communications device, a connection release message indicating that the communications device is to release a connection between the communications device and the infrastructure equipment, wherein the connection release message comprises an indicator that the mobility procedure comprises switching from the first wireless communications network to the second wireless communications network.

48. A method according to Claim 47, wherein the indicator explicitly identifies the second wireless communications network.

49. A method according to Claim 47, wherein the indicator identifies a second frequency band, the second frequency band being a frequency band within which the communications device is to transmit the signals to and/or receive the signals from the second wireless communications network and being different to a first frequency band within which the signals transmitted to and/or received from the infrastructure equipment are transmitted and/or received.

50. A method according to Claim 47, wherein the indicator is included within a cell reselection priority list and indicates a priority of the second wireless communications network.

51. A method according to Claim 47, wherein the indicator is included within the connection release message separately to a cell reselection priority list.

52. A method according to Claim 47, wherein the indicator indicates one or more conditions under which the communications device is to perform the mobility procedure by switching from the first wireless communications network to the second wireless communications network.

53. A method according to Claim 35, wherein the performing the mobility procedure comprises receiving, from the communications device, an indication of a sustainability profile associated with the communications device, and transmitting, based on the received indication of the sustainability profile, an indication that the communications device is to perform the mobility procedure from the first wireless communications network to the second wireless communications network.

54. A method according to Claim 53, wherein the indication of the sustainability profde is received, within random access control, RACH, resources of the wireless radio interface, as part of a RACH message, and wherein the RACH resources are reserved for energy efficient communications devices.

55. A method according to Claim 35, comprising receiving, from the communications device if a specified condition is satisfied, an indication of measured reference signals received by the communications device from the second wireless communications network.

56. A method according to Claim 55, wherein the specified condition comprises a quality of the measured reference signals being above a threshold.

57. A method according to Claim 55, wherein the specified condition comprises a quality of the measured reference signals being higher than a quality of measured reference signals received from the infrastructure equipment.

58. A method according to Claim 55, wherein the specified condition comprises a quality of the measured reference signals being more than a specified amount higher than a quality of measured reference signals received from the infrastructure equipment.

59. A method according to Claim 35, comprising receiving, from the second wireless communications network after the mobility procedure has been performed, data transmitted by the communications device to the second wireless communications network, and transmitting, to a core network, the received data.

60. An infrastructure equipment forming part of a first wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, to perform a mobility procedure with the communications device, and to determine that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network.

61. Circuitry for an infrastructure equipment forming part of a first wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to transmit signals to and/or to receive signals from a communications device, whilst the communications device is located within a coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment, to perform a mobility procedure with the communications device, and to determine that the mobility procedure comprises the communications device switching from the first wireless communications network to a second wireless communications network whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network.

62. A method of operating an infrastructure equipment forming part of a second wireless communications network, the method comprising performing a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and transmitting signals to and/or receiving signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

63. A method according to Claim 62, wherein the first wireless communications network and the second wireless communications network are controlled by different network operators.

64. A method according to Claim 62, wherein the signals transmitted to and/or received from the communications device are transmitted and/or received within a second frequency band, the second frequency band being different to a first frequency band in which the communications device is to transmit signals to and/or receive signals from the first wireless communications network before the mobility procedure has been performed.

65. A method according to Claim 62, wherein the coverage region of the first wireless communications network and the coverage region of the second wireless communications network are both within a predefined geographic area which is defined by a national border, a regional border, or a political border.

66. A method according to Claim 65, wherein the coverage region of the first wireless communications network is defined by a first public land mobile network, PLMN, of a first network operator within the predefined geographic area, and wherein the coverage region of the second wireless communications network is defined by a second PLMN of a second network operator within the predefined geographic area.

67. A method according to Claim 62, comprising receiving data from the communications device after the mobility procedure has been performed, and transmitting, to a core network, the data received from the communications device.

68. A method according to Claim 67, wherein the core network is common to the first wireless communications network and the second wireless communications network.

69. A method according to Claim 67, wherein the data is transmitted to a packet gateway of the core network, wherein the packet gateway is common to the first wireless communications network and the second wireless communications network.

70. A method according to Claim 67, wherein the core network and the second wireless communications network are both controlled by a second network operator, the second network operator being different to a first network operator controlling the first wireless communications network.

71. A method according to Claim 70, wherein the infrastructure equipment transmits signals to and/or receives signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network.

72. A method according to Claim 71, wherein the infrastructure equipment transmits signals to and/or receives signals from the communications device on behalf of both of the first wireless communications network and the second wireless communications network dependent on one or both of a quality of signals transmitted between the communications device and the infrastructure equipment and a sustainability profile associated with the communications device.

73. A method according to Claim 62, comprising receiving data from the communications device after the mobility procedure has been performed, and transmitting, to the first wireless communications network, the data received from the communications device for forwarding, by the first wireless communications network, to a core network.

74. An infrastructure equipment forming part of a second wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to perform a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

75. Circuitry for an infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to perform a mobility procedure with a communications device which is currently connected to a first wireless communications network for transmitting and/or receiving signals whilst the communications device is located within a coverage region of the first wireless communications network, wherein the mobility procedure comprises the communications device switching from the first wireless communications network to the second wireless communications network, and to transmit signals to and/or to receive signals from the communications device, whilst the communications device is simultaneously located within both of a coverage region of the second wireless communications network and the coverage region of the first wireless communications network, via a wireless radio interface provided by the infrastructure equipment.

76. A wireless communications system comprising a communications device according to Claim 33 and at least one of an infrastructure equipment according to Claim 60 and an infrastructure equipment according to Claim 74.

77. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Claim 1, Claim 35, or Claim 62.

78. A non-transitory computer-readable storage medium storing a computer program according to Claim 77.