EP4666675A1

EP4666675A1 - Communications devices, infrastructure equipment and methods

Info

Publication number: EP4666675A1
Application number: EP24703773.2A
Authority: EP
Inventors: Vivek Sharma; Yuxin Wei; Yassin Aden Awad; Hideji Wakabayashi
Original assignee: Sony Europe BV; Sony Group Corp
Current assignee: Sony Europe BV; Sony Group Corp
Priority date: 2023-02-15
Filing date: 2024-02-06
Publication date: 2025-12-24
Also published as: WO2024170356A1

Abstract

A communications device and a method of operating a communications device, which is configured to transmit data via a wireless communications network. The communications device is configured to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication. The adjusting the evaluation may include discounting measurement samples from signals being used to evaluate a cell, when these signals have not been transmitted because the infrastructure equipment of the cell has entered a sleep state. In other examples, the adjusting the evaluation may comprise increasing a period over which the evaluation of the signal measurements for determining the one or more conditions for handover with respect to a period for performing the evaluation for a cell which is not in sleep state.

Description

COMMUNICATIONS DEVICES, INFRASTRUCTURE EQUIPMENT AND METHODS

BACKGROUND

Field

The present disclosure relates to communications devices, infrastructure equipment of a wireless communications network and methods of operating communications devices and infrastructure equipment of a wireless communications network in which reference signals are measured and evaluated as part of a process performed by one or both of the communications devices and the infrastructure equipment. The present disclosure claims the Paris convention priority to European patent application number EP23156909.6 filed on 15 February 2023 the contents of which are incorporated herein by reference in their entirety.

Description of Related Art

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

3GPP defined wireless communications systems are able to support more sophisticated services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. UMTS and Long Term Evolution (LTE) systems are able to support high data rate applications such as mobile video streaming and mobile video conferencing that is comparable with 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, may be expected to increase ever more rapidly.

With further developments, wireless communications networks can support a wider range of devices associated with a wider range of data traffic profiles and types. For example, it is expected that future wireless communications networks will be expected to support efficiently communications with an increasing range of devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance.

Wireless communications networks, for example those which may be referred to as 5G or new radio (NR) system / new radio access technology (RAT) systems [1], as well as future iterations / releases of existing systems, can support connectivity for an increased diversity of devices associated with different applications and different characteristic data traffic profiles.

Communications devices are configured to operate with a wireless communications system to perform various processes and procedures in order to maintain connectivity. For example, the connectivity of devices is conventionally maintained through the use of so-called “handover” procedures where a communications device changes its access point to a wireless communications network in response to an instruction from the wireless communications network or in response to one or more conditions being met. The instruction from the wireless communications network as well as the one or more conditions are typically based on measurements of signals received from a source infrastructure equipment and one or more neighbouring infrastructure equipment in order to identify a target infrastructure equipment for the handover and whether the one or more conditions have been satisfied. More generally there is a desire to improve an accuracy of measurements in view of adaptations and developments to wireless communications networks of which handover is one example. SUMMARY

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

Example embodiments can provide a communications device and a method of operating a communications device, which is configured to transmit data via a wireless communications network. The communications device is configured to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication. The adjusting the evaluation may include discounting measurement samples from signals being used to evaluate a cell, when these signals have not been transmitted because the infrastructure equipment of the cell has entered a sleep state. In other examples, the adjusting the evaluation may comprise increasing a period over which the evaluation of the signal measurements for determining the one or more conditions for handover with respect to a period for performing the evaluation for a cell which is not in sleep state.

In some example embodiments, the process performed by the communications device for which the signal measurements are performed and evaluated is part of a conditional handover process, the serving infrastructure equipment of the serving cell being a source infrastructure equipment and the one or more neighbouring cells provided by the neighbouring infrastructure equipment are evaluated to identify a target infrastructure equipment for handover. As such, the communications device is configured to receive, from the serving infrastructure equipment, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from the one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and to adjust the evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover. However handover is just one example application of a technique which adjusts measurements or the evaluation of measurements according to a sleep cycle of infrastructure equipment of the network.

Example embodiments can also provide a method of operating a source infrastructure equipment of a wireless communications network in a conditional handover, the method comprising configuring one or more conditions for triggering a handover of a communications device from a source cell currently serving a communications device provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communications network, the target infrastructure equipment being identified from one or more neighbouring infrastructure equipment providing one or more neighbouring cells, transmitting, to the communications device, an indication of the one or more conditions for triggering the handover of the communications device from the source cell to the target cell. The method comprises determining that one or more the source infrastructure equipment and one or more of the neighbouring infrastructure equipment has or will enter a sleep state in which signal measurements for evaluating the one or more conditions for triggering the handover cannot be made, and transmitting an indication that the one or more the source infrastructure equipment and one or more of the neighbouring infrastructure equipment has or will enter a sleep state to the communications device, for use by the communications device in adjusting an evaluation of the one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover. Embodiments can provide an adaptation of an evaluation of measurements of signals received from a source cell or one or more neighbouring cells to account for a sleep state of infrastructure equipment forming the cell so as to more accurately assess whether conditions for performing handover are met in an energy efficient network.

Respective aspects and features of the present disclosure are defined in the appended claims, which include an infrastructure equipment and methods of operating infrastructure equipment and communications devices.

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:

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 of a source infrastructure equipment controlling handover of a communications device to a target infrastructure equipment;

Figure 4 schematically represents a conventional conditional handover procedure;

Figure 5 is a schematic representation of a communications device performing measurements as part of a conditional handover procedure;

Figure 6 is a graphical representation of a plot of example signals which are used for performing measurements of a serving or source cell or neighbouring cells shown with respect to sleep states of an infrastructure equipment forming the cells;

Figure 7 is a flow diagram illustrating a method of operating a source infrastructure equipment of a wireless communications network in a conditional handover in accordance with example embodiments; and

Figure 8 is a flow diagram illustrating a method of operating a communications device in a conditional handover in accordance with example embodiments.

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 100 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 [2] . 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 100 includes a plurality of base stations 101 connected to a core network part 102. Each base station provides a coverage area 103 (e.g. a cell) within which data can be communicated to and from communications devices 104. Data is transmitted from the base stations 101 to the communications devices 104 within their respective coverage areas 103 via a radio downlink. Data is transmitted from the communications devices 104 to the base stations 101 via a radio uplink. The core network part 102 routes data to and from the communications devices 104 via the respective base stations 101 and provides functions such as authentication, mobility management, charging and so on. Communications devices may also be referred to as mobile stations, user equipment (UE), user terminals, mobile radios, terminal devices, and so forth. Base stations, which are an example of network infrastructure equipment / network access nodes, may also be referred to as transceiver stations / nodeBs / e-nodeBs, 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, example embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems such as 5G or new radio as explained below, 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)

Figure 2 is a schematic diagram illustrating a network architecture for a new RAT wireless communications network / system 200 based on previously proposed approaches which may also be adapted to provide functionality in accordance with embodiments of the disclosure described herein. The new RAT network 200 represented in Figure 2 comprises a first communication cell 201 and a second communication cell 202. Each communication cell 201, 202, comprises a controlling node (centralised unit) 221, 222 in communication with a core network component 210 over a respective wired or wireless link 251, 252. The respective controlling nodes 221, 222 are also each in communication with a plurality of distributed units (radio access nodes / remote transmission and reception points (TRPs)) 211, 212 in their respective cells. Again, these communications may be over respective wired or wireless links. The distributed units 211, 212 are responsible for providing the radio access interface for communications devices connected to the network. Each distributed unit 211, 212 has a coverage area (radio access footprint) 241, 242 where the sum of the coverage areas of the distributed units under the control of a controlling node together define the coverage of the respective communication cells 201, 202. Each distributed unit 211, 212 includes transceiver circuitry for transmission and reception of wireless signals and processor circuitry configured to control the respective distributed units 211, 212.

In terms of broad top-level functionality, the core network component 210 of the new RAT communications network represented in Figure 2 may be broadly considered to correspond with the core network 102 represented in Figure 1, and the respective controlling nodes 221, 222 and their associated distributed units / TRPs 211, 212 may be broadly considered to provide functionality corresponding to the base stations 101 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 communications 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 / centralised unit and / or the distributed units / TRPs. A communications device or UE 260 is represented in Figure 2 within the coverage area of the first communication cell 201. This communications device 260 may thus exchange signalling with the first controlling node 221 in the first communication cell via one of the distributed units 211 associated with the first communication cell 201. In some cases communications for a given communications device are routed through only one of the distributed units, but it will be appreciated that in some other implementations communications associated with a given communications device may be routed through more than one distributed unit, for example in a soft handover scenario and other scenarios.

In the example of Figure 2, two communication cells 201, 202 and one communications device 260 are shown for simplicity, but it will of course be appreciated that in practice the system may comprise a larger number of communication cells (each supported by a respective controlling node and plurality of distributed units) serving a larger number of communications devices.

It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT communications 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 communications systems having different architectures.

Thus example 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 that the specific wireless communications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, example 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 101 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 / access node may comprise a control unit / controlling node 221, 222 and / or a TRP 211, 212 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

A detailed illustration of a wireless communications network in which a handover may be performed is shown in Figure 3. As will be appreciated from Figure 3, a communications device 502 is handed over from a source cell provided by a source infrastructure equipment 504 to a target cell provided by the target infrastructure equipment 506. The source and target cells are not shown in Figure 3 for clarity, although it will be appreciated that the source and target cells may broadly correspond to cells 3, 12 as discussed in relation to Figures 1 and 2 above. The source infrastructure equipment 504 and target infrastructure equipment 506 form part of a radio access network to a core network 508. As will be appreciated the communications device 502 is an example of a communications device such as the communications device 260 of Figure 2. The communications device 502 may be a UE in one example.

Before the handover, the communications device 502 transmits signals on an uplink UL and receives signals on a downlink DL from a source infrastructure equipment 504. The source infrastructure equipment 504 and the target infrastructure equipment 506 may each be thought of as a gNB 101 or a combination of a controlling node 221 and TRP 211. Before the handover, the communications device 502 is shown to transmit uplink data to the source infrastructure equipment 504 via uplink resources UL of a wireless access interface as illustrated generally by dashed arrow 274b to the source infrastructure equipment 504. The communications device 502 may similarly be configured to receive downlink data transmitted by the source infrastructure equipment 504 via downlink resources DL as indicated by dashed arrow 288b from the source infrastructure equipment 504 to the communications device 502. After the handover, the communications device 502 is shown to transmit uplink data to the target infrastructure equipment 506 via uplink resources UL of a wireless access interface as illustrated generally by solid arrow 288a to the target infrastructure equipment 506. The communications device 502 may similarly be configured to receive downlink data transmitted by the target infrastructure equipment 506 via downlink resources DL as indicated by solid arrow 274a from the target infrastructure equipment 506 to the communications device 502.

In Figure 3, the source and target infrastructure equipment 504, 506 are each connected to a core network 508 via interfaces 278, 279 to a controller 504c, 506c of the respective infrastructure equipment 504. The source and target infrastructure equipment 504, 506 each include a receiver 504b, 506b connected to an antenna 504d, 506d and a transmitter 504a, 506a connected to the antenna 504d, 506d. Correspondingly, the communications device 502 includes a controller 502c connected to a receiver 502b which receives signals from an antenna 502d and a transmitter 502a also connected to the antenna 502d.

The controllers 504c, 506care configured to control the source and target infrastructure equipment 504, 506 respectively 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 controllers 504c, 506c 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 504a, 506a and the receivers 504b, 506b may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitters 504a, 506a the receivers 504b, 506b and the controllers 504c, 506c 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 504 will in general comprise various other elements associated with its operating functionality.

Correspondingly, the controller 502c of the communications device 502 is configured to control the transmitter 502a and the receiver 502b 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 502c 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 502a and the receiver 502b may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitters 502a, receivers 502b, and controllers 502c 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 communications device 502 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 3 in the interests of simplicity.

The controllers 504c, 502c 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. Example embodiments of the present technique provide improvements in an accuracy of measuring signal quality in a cell formed by an infrastructure equipment in which that infrastructure equipment enters a sleep cycle so that a measurement of signals received from the infrastructure equipment are adjusted when evaluating the measured signal in accordance with the sleep cycle. A more accurate assessment of a signal quality from cell can be thereby achieved. The signals may be measured and evaluated as part of a process or procedure performed by the communications device and/or the wireless indications network. In one example the process is a handover process or conditional handover. However other examples may also use an adjustment of an evaluation of measured signals such as a cell selection or re-selection procedure when a communications device is in an RRC inactive or idle state. However in order to gain a better understanding of example embodiments, the following paragraphs describe an example of conditional handover, although it will be appreciated that this is just one example of a process performed by a communications device using evaluated measurements.

Conventional Conditional Handover

Aspects of NR are concerned with mobility enhancements and in particular with increasing mobility robustness for new services which require low latency and high reliability performance (such as URLLC). Situations may arise where a cell currently serving a UE may no longer be suitable or a radio link between the UE and a source gNB providing coverage in the cell is degraded. In such situations, it is generally desirable for the UE to switch to being served by a cell of a target gNB. One way of configuring a handover of a UE from a source gNB to a target gNB is referred to as a “conditional handover”.

An example of a conditional handover is illustrated in Figure 4 which is reproduced from [3], the contents of which are incorporated by reference in their entirety. Figure 4 schematically represents communications in a wireless communications network between the communications device 502, the source infrastructure equipment 504, the target infrastructure equipment 506, other potential target infrastructure equipment 511, an Access Mobility and Mobility Management Function (AMF) 512 and a User Plane Function (UPF) 514. In Figure 4, the source infrastructure equipment 504, the target infrastructure equipment 506, other potential target infrastructure equipment 511 are depicted as “gNBs”, although it will be appreciated that other infrastructure equipment of a wireless communications network could be used (such as eNBs for example). The AMF 512 and UPF 514 are functions in a core network of the wireless communications network (such as core network 508).

As shown in Figure 4, before a handover, the communications device 502 communicates user plane data with the AMF 512 and UPF 514 via the source infrastructure equipment 504. In step 0, the AMF 512 provides mobility control information to the source infrastructure equipment 504. In step 1, the communications device 502 reports measurements to the source infrastructure equipment 504. Such measurements may include measurements performed by the communications device 502 such as a Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ) and/or a Signal-to- Interference Ratio (SINR) of reference signals from the source infrastructure equipment 504, the target infrastructure equipment 506 and/or the other potential target infrastructure equipment 511. The RSRP, the RSRQ and the SINR may be collectively referred to as Radio Resource Management (RRM) measurements. In step 2, the source infrastructure equipment 504 determines to configure the communications device 502 for a conditional handover. In step 3, the source infrastructure equipment 504 transmits a handover request to the target infrastructure equipment 506 and the other potential target infrastructure equipment 511. In response, in step 4, the target infrastructure equipment 506 and the other potential target infrastructure equipment 511 perform admission control. Then, in step 5, the target infrastructure equipment 506 and the other potential target infrastructure equipment 511 transmit a handover request acknowledgement to the source infrastructure equipment 504. In response to receiving the handover request acknowledgement, the source infrastructure equipment 504 transmits, in step 6, a conditional handover configuration message to the communications device 502. The conditional handover configuration message may be a Radio Resource Control (RRC) configuration message. The conditional handover configuration message includes one or more conditions for triggering a handover of the communications device 502 from a source cell provided by the source infrastructure equipment 504. For example, the one or more conditions in the conditional handover configuration message may include one or more conditions to be met for triggering a handover to target cell provided by the target infrastructure equipment 506 and one or more other conditions to be met for triggering a handover to the other target cells provided by other potential target infrastructure equipment 511. The conditions included in the conditional handover configuration message are explained in more detail below. After receiving the conditional handover configuration message, the communications device 502 transmits an RRC reconfiguration complete message to the source infrastructure equipment 504. After receiving the conditional handover configuration message, the communications device 502 may continuously or periodically evaluate the conditions included in the handover configuration message for triggering the handover to determine whether the conditions for triggering the handover have been met. When the communications device 502 determines that conditions for triggering the handover have been met, the communications device 502 initiates the handover. For example, the communications device 502 detaches from the source cell provided by the source infrastructure equipment 504 and attaches to the target cell provided by the target infrastructure equipment 506. In the example shown in Figure 4, the communications device 502 determines that the conditions for triggering a handover to the target infrastructure equipment 506 are met. While the communications device 502 is evaluating the conditions, the source infrastructure equipment 604 transmits an early status transfer to the other potential target infrastructure equipment in step 7a, and subsequent user data from the UPF 514 is routed to the other potential target infrastructure equipment 511 via the source infrastructure equipment 504. In step 8, the target infrastructure equipment 506 determines that the handover of the communications device 502 from the source cell provided by the source infrastructure equipment 504 to the target cell provided by the target infrastructure equipment 506 has been successful. In response, the target infrastructure equipment 506 transmits a handover success message to the source infrastructure equipment 504 in step 8a. In step 8b, the source infrastructure equipment 504 transmits an SN status transfer message to the target infrastructure equipment 506. Subsequent user data from the UPF 514 to the source infrastructure equipment is routed to the target infrastructure equipment 506. In step 8c, a handover cancel message is transmitted from the source infrastructure equipment 504 to the target infrastructure equipment and the other potential target infrastructure equipment 511.

As mentioned above in step 6 of Figure 4, the source infrastructure equipment 504 may transmit a conditional handover configuration message to the communications device 502 including one or more conditions for triggering the handover.

An example of a condition to be met for triggering a handover of the communications device 502 is “event A3”. The condition defined by event A3 is met if a signal quality of a cell provided by a neighbouring infrastructure equipment (for example, the target infrastructure equipment 506 or the other potential target infrastructure equipment 511) becomes a pre-defined offset higher than the signal quality of a cell provided by the source infrastructure equipment 504.

Another example of a condition to be met for triggering a handover of the communications device 502 is “event A4”. The condition defined by event A4 is met if the signal quality of the cell provided by the neighbouring infrastructure equipment is greater than an absolute threshold.

Another example of a condition to be met for triggering a handover of the communications device 502 is “event A5”. The condition defined by event A5 is met if the signal quality of the cell provided by the source infrastructure equipment 504 is less than an absolute threshold and the signal quality of the neighbouring infrastructure equipment is greater than an absolute threshold.

The “signal quality” mentioned above in respect of the definitions of events A3, A4 and A5 may be measured by the communications device 502 using one or more signal quality parameters such as RSRP, RSRQ and SINR. For example, the communications device 502 may determine that condition outlined in event A3 may be met if a measured RSRP of the cell provided by the neighbouring infrastructure equipment becomes a pre-defined offset higher than the measured RSRP for the cell provided by the source infrastructure equipment 504. In another example, may determine that condition outlined in event A3 is met if a measured RSRP and RSRQ of the cell provided by the neighbouring infrastructure equipment each respectively become a pre-defined offset higher than the measured RSRP and RSRQ for the cell provided by the source infrastructure equipment 504. In Release-16 of standards of the 3GPP group, only one reference signal type and measurements of at most two signal quality parameters are supported in determining whether event A3, A4 and/or A5 are met.

Each of events A3, A4 and A5 therefore each represent a condition for triggering a handover of the communications device 502 from the source infrastructure equipment 504. In order to trigger the handover, it may be sufficient that only one condition included in the conditional handover configuration message is met, or the triggering of the handover may require more than one or all of the conditions in the conditional handover configuration message to be met. In one example, only event A3 is included as a condition and the handover is triggered if event A3 is met. In another example, both events A3 and A4 are included as conditions and the handover is triggered if either event A3 or A4 is met. In another example, both events A3 and A4 are included as conditions and the handover is triggered if both events A3 or A4 are met.

Further details of events A3, A4 and A5 are provided in TS 36.331 which is hereby incorporated by reference in its entirety.

Network Energy Saving (NES)

In Release- 18 of the 3PP standards, a new study item has been initiated on Network Energy Saving (NES) ([4]). The objectives of the study item are the following:

(i) Defining a base station energy consumption model

Objective (i) is expected to include adapting frameworks of power consumption modelling and evaluation methodologies for UE power saving in NR (discussed in [5]) to the base station side. This is expected to involve adapting relative energy consumption for DL and UL (considering factors such as Power Amplifier (PA) efficiency, number of TXRU interfaces, base station load, etc), sleep states and associated transition times, and one or more reference parameters/configurations.

(ii) Defining of an evaluation methodology and Key Performance Indicators (KPIs)

Objective (ii) is expected to include targeting the evaluation methodology for evaluating system-level network energy consumption and energy savings gains, as well as assessing/balancing impact to network and user performance (for example, spectral efficiency, capacity, User Perceived Throughput (UPT), latency, handover performance, call drop rate, initial access performance, Service Level Agreement (SLA) assurance related KPIs), energy efficiency, UE power consumption, and complexity. The evaluation methodology is expected to focus on reusing existing KPIs whenever applicable, rather than focussing on a single KPI. Where existing KPIs are found to be insufficient, new KPIs may be developed as needed. It has yet to be determined which KPIs will be evaluated and how.

(iii) Identifying techniques on the gNB and UE side to improve network energy savings in terms of both base station transmission and reception

Objective (iii) is expected to include achieving efficient operation dynamically and/or semi-statically and finer granularity adaptation of transmissions and/or receptions in one or more of network energy saving techniques in time, frequency, spatial, and power domains, with potential support/feedback from UE, and potential UE assistance information. Objective (iii) is also expected to include information exchange/coordination over network interfaces.

The study item is expected to prioritize idle/empty and low/medium load scenarios, with different loads among carriers and neighbour cells being permitted. The exact definition of such loads is expected to be determined as part of the study item.

The following examples of single-carrier and multi-carrier deployments are expected to be prioritized in the study item:

- Urban micro in FR1, including Time Division Duplex (TDD) massive Multiple-Input Multiple- Output (MIMO). This can also model small cells.

- FR2 beam-based scenarios (note: this scenario can also model small cells)

- Urban/Rural macro in FR1 with/without DSS Dynamic Spectrum Sharing (DSS). No impact to LTE expected in case of DSS.

- Evolved-Universal Terrestrial Radio Access-New Radio Dual Connectivity (EN-DC)ZNew Radio Dual Connectivity (NR-DC) macro with Frequency Division Duplex (FDD) Primary Cell (PCell) and TDD/Massive MIMO on higher FR1/FR2 frequency

It intended that existing UEs will be able to continue accessing a network implementing Release- 18 network energy savings techniques, with the possible exception of techniques developed specifically for greenfield deployments.

Network Energy Saving (NES) Modes

It has been proposed that cells provided by infrastructure equipment of a wireless communications network are configured to operate in accordance with NES modes. Table 1 (reproduced from [6]) illustrates examples of proposed NES modes.

Table 1. Proposed NES modes.

In Table 1, the transition time, T, for an NES mode is the time taken for a cell to enter or leave that NES mode. The additional transition energy, E, for an NES mode is the energy required for a cell to enter or leave that NES mode relative to a reference energy. The relative power, P, of an NES mode is the power consumed when a cell enters of leaves that NES mode relative to a reference power.

As will be understood by one skilled in the art, the relative power for the deep sleep NES mode is lower than the relative power for the light sleep NES mode which is lower than the relative power for micro sleep NES mode. In other words, Pl < P2 < P3. Furthermore, as will be understood by one skilled in the art, the relative power of the active UL NES mode has a lower relative power than the active DL NES mode. In other words, P5 < P4.

Table 2 (reproduced from [6]) illustrates examples of relative power, P, values for the NES modes shown in Table 1 across different base station categories and reference configuration sets. Further detail on the base station categories and the reference configuration sets can be found in [6] .

Table 2. Relative Power of Proposed NES modes.

In addition to NES modes proposed in Table 1, other NES modes are envisaged. For example, a cell may be configured to operate in accordance with an NES mode which has a relative power lower than the deep sleep NES mode and requires a larger transition time. This may be referred to as a hibernating sleep, or Quasi-off, NES mode. Another example of an NES mode is an “OFF” NES mode where the cell is turned off for uplink and downlink transmissions.

Furthermore, in NES mode, a gNB may operate according to the following examples:

• Example 1 : gNB is expected to turn off all transmission and reception for data traffic and reference signal during Cell DTX/DRX non-active periods.

• Example 2: gNB is expected to turn off its transmission/reception only for data traffic during Cell DTX/DRX non-active periods (i.e., gNB will still transmit/receive reference signals)

• Example 3: gNB is expected to turn off its dynamic data transmission/reception during Cell DTX/DRX non-active periods (i.e., gNB is expected to still perform transmission/reception in periodic resources, including SPS, CG-PUSCH, SR, RACH, and SRS).

• Example 4: gNB is expected to only transmit reference signals (e.g., CSI-RS for measurement).

Cell discontinuous transmission, DTX, mode and configuration can also be indicated to the UE via dynamic L1/L2 signalling. The dynamic L1/L2 signalling at least supports UE dedicated indication. Whether a UE group common signalling is also supported will be further studied.

It is beneficial to align UE discontinuous reception, DRX, with Cell DTX and DRX alignment among multiple UEs. Cell DTX/DRX information is considered necessary to be exchanged and coordinated between neighbour gNBs. The gNB can use the received cell DTX/DTX information to determine its own cell DTX/DRX configuration for network energy saving purpose. Configuring network cells to operate in accordance with NES modes is expected to improve network energy savings. For example, in accordance with a network planning strategy, different cells in a wireless communications network may operate according to different NES modes. For example, a cell may be configured in a micro sleep NES mode when uplink/downlink traffic is expected imminently in the cell and another cell may be configured in a deep sleep NES mode when uplink/downlink traffic is not expected in the cell for considerable time.

Enhancements to conditional handover for NES have been discussed in [6] and [7], both of which are hereby incorporated by reference in their entirety. In particular, it has been proposed to enhance conditional handover by making the evaluation of conditional handover conditions dependent on the NES mode of the source/target cell. However, in existing conditional handover procedures, communications devices periodically or continuously evaluate handover conditions which can lead to energy wastage. Furthermore, communications devices may not be aware of changes, or expected changes, in NES modes of cells in the wireless communications network. Communications devices may therefore spend too long in cells with NES modes to which the communications device is not suited, leading to further energy wastage. For example, a communications device may be in a cell which has just turned on an NES mode, but the communications device cannot be offloaded to another cell until it evaluates the conditions for handover. Therefore, improving the energy efficiency of conditional handover presents technical challenges.

There is therefore a need for communications devices, infrastructure equipment and methods for improving the energy efficiency of conditional handover in wireless communications networks. This may be particularly appropriate since the duration of the sleep deep sleep may be longer than 50 ms or 10 seconds depending on the type of base station (reference 3 GPP based TR 38.864).

Connected Mode Mobility

During the switching of NES modes, it is possible to handover the UEs faster by enhancing the CHO procedure by evaluating conditional handover conditions depending on the NES state of source/target cell. Whenever mobility from source cell is triggered, the NES mode of the target cell could also be considered, e.g., to avoid UEs selecting cells operating in NES mode if any other cell is available. When a base station is in NES deep sleep state then it may not broadcast reference signals and sleep duration may be fixed or change dynamically depending on load conditions and other factors. As such, measurements which are usually performed in order to trigger CHO may be affected. This is explained below with reference to Figures 5 and 6.

In Figure 5 a UE 502 is shown in a state in which it is currently attached to a source gNB 504. The UE 502 is therefore in a connected state and communicating data to and from the gNB 504. In accordance with a known handover technique, the UE 502 performs measurements of received signals such as a PBCH or a CSI-RS in order to determine whether or not one or more neighbouring gNBs have better a signal strength and therefore can provide better communications quality in accordance with the CHO techniques explained above. According to this conventional arrangement, the UE 502 therefore performs RRM measures of signals from a source and neighbouring base stations in order to identify a target gNB cell 506. In order to determine whether the CHO conditions are met, the UE 502 for example measures a signal strength both from its source gNB 504 therefore and other neighbouring gNB’s 506, 530.

As shown in Figure 5 an expanded view of functional elements of the UE 502 is shown, which serve to determine measurements of both the source gNB 504 and neighbouring gNB’s 506, 513. A receiver 502b in the UE 502 measures signal quality from known signals of the neighbouring gNB’s 506, 533 and feeds these measurements to a filter 532. The filter 532 filters the measurements to generate at its output an indication of signal quality based on a plurality of samples gathered from respective gNB’s 504, 506 12 513, according to a sampling rate determined by measureable signals (PBCH or CSI-RS) which can be transmitted and received.

In one example, the filter 532 performs a layer 3 filtering as specified in TS 38.331 according to the formula below:

F_a = (1 - a)*F_a-i + a*M_a where

M„ is the latest received measurement result from the physical layer;

F„ is the updated filtered measurement result, that is used for evaluation of reporting criteria or for measurement reporting;

F„-i is the old filtered measurement result, where Fo is set to Mi when the first measurement result from the physical layer is received; and for MeasObjectNR, a = l/2^(A,/4), where k, is the filterCoefficient for the corresponding measurement quantity of the i:th QuantityConfigNR in quantityConfigNR-List, and i is indicated by quantityConfiglndex in MeasObjectNR,' for other measurements, a = l/2^(A/4), where k is the filterCoefficient for the corresponding measurement quantity received by the quantityConfig,' for UTRA- FDD, a = l/2^(k/4)’ where k is the filterCoefficient for the corresponding measurement quantity received by quantityConfigUTRA-FDD in the QuantityConfig,'

Time characteristics of the filter are preserved at different input rates, observing that the filterCoefficient k assumes a sample rate equal to X ms. The value of X is equivalent to one intra-frequency LI measurement period as defined in TS 38. 133 [14] assuming non-DRX operation, and depends on frequency range.

An output of the filter 532 is fed to the controller 502c which controls the receiver 502b. Therefore according to the resulting signal strength measurements, the controller 502c of the UE 502 determines whether any of the CHO conditions are met for performing CHO as explained above. Usually, new samples have more weight than old samples and samples with zero/almost zero measurement values will reduce an overall measurement result due to filtering process. Therefore, what happens when one or more of the gNB’s 506 enter a sleep sate and therefore do not transmit signals such as the PBCH or CSI-RS for which samples of signal strength are used to feed the filter 532?

As will be appreciated from the above explanation, an NES state may have a sleep duration in which the sleep period overlaps with the periodicity of SSB and/or CSI-RS. If a target gNB operates with an NES state of example 1 mentioned above (gNB turns off all transmission and reception for data traffic and references signal during Cell DTX/DRX non-active periods) the target gNB cell may not transmit any reference signals for a period during which the UE is evaluating a CHO conditions. As such, evaluation measurements can give a false representation of a true signal quality available from the target gNB. This is because as explained above, zero measurements will have an effect of indicating a lower signal strength measurements. Figure 5 provides a graphical illustration of an example in which NES states mean that SSB measurements from PBCH transmitted by the target gNB may not be available.

For the example shown in Figure 6, it is assumed that the NES sleep state is aligned with subframe boundary but this is not necessary true. It is also assumed that a sleep state is shown in a periodic (showing a pattern), although the sleep state could be a one off sleep state based on traffic, time of the day and predicted traffic. Furthermore, a gNB cell may not transmit any signal during NES sleep state or transmit with reduced power. Example embodiments can provide a communications device or a method of operating a communications device in a wireless communications network comprising measuring signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, evaluating the signal measurements as part of a process performed by the communications device, receiving an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and the evaluating the signal measurements, adjusting the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication. The adjusting the evaluation may include discounting measurement samples from signals being used to evaluate a cell, when these signals have not been transmitted because the infrastructure equipment of the cell has entered a sleep state or adjusting an evaluation period in proportion with a sleep state of a sleep cycle of an NES infrastructure equipment.

Embodiments can provide a method of operating a communications device in a conditional handover, the method comprising receiving, from a source infrastructure equipment of a wireless communications network forming a source cell currently serving the communications device, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from one or more neighbouring infrastructure equipment providing one or more neighbouring cells. The method comprises receiving, from the source infrastructure equipment, an indication of the one or more conditions for triggering the handover of the communications device from the source cell to the target cell, receiving an indication that the one or more of the source infrastructure equipment and the one or more of the neighbouring infrastructure equipment has or will enter a sleep state, and adjusting an evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover. The adjusting the evaluation may include discounting measurement samples from signals being used to evaluate a cell, when these signals have not been transmitted because the infrastructure equipment of the cell has entered a sleep state. In other examples, the adjusting the evaluation may comprise increasing a period over which the evaluation of the signal measurements for determining the one or more conditions for handover with respect to a period for performing the evaluation for a cell which is not in sleep state.

Example embodiments can configure a UE to receive an indication of one or more neighbouring cell DTX/DRX state and optionally along with a Cell DTX/DRX pattern (periodic/aperiodic/one-shot) or duration for which reference signals are not transmitted during the Cell DTX/DRX periods. Accordingly, the UE measurements carried out during the time when reference signals are not transmitted does not affect UE measurement accuracy.

According to example embodiments an SMTC duration configuration (SMTC = SS/PBCH measurement timing configuration) may be configured and used by a communications device. An SMTC is identified in 3GPP specifications for an SSB-based RRM Measurement Timing Configuration (SMTC) window is notified to a UE. Normally a UE performs measurements based on an SMTC configuration. The configuration informs and contains a periodicity and a Physical Cell ID (PCI) range/frequency for which this SMTC periodicity is valid. A maximum value of an SMTC duration is 160 msecs and with NES, a cell may not transmit SSB/CSI-RS for a longer period of time. According to some embodiments, the SMTC value may be lengthened for example to a new value of 320 msec or longer. As will be appreciated, this value is just an example and other longer SMTC lengths may be used which have an increased temporal length compared to SMTC lengths for gNBs which are not in an NES state. In other examples, the SMTC value may be adjusted dynamically because a cell DTX/DRX may be adjusted dynamically. For example, a cell is switched off for longer periods during night-time (say in several hours), but it could be few seconds or msecs during the day-time.

For example, embodiments in which the SMTC is changed dynamically with the cell DTX/DRX period, UEs may be signalled the SMTC using a MAC/PHY signalling. For example, a new MAC-CE could be introduced indicating that a particular neighbouring cell has moved to a NES state and additionally including a start and an end time of an NES sleep state. This MAC-CE is sent from the serving or source cell to the UEs. Serving cell receives this information (i.e., neighbour cell DTX/DRX pattern) from the target cell via Xn interface or potentially new DU-DU interface. The UE will then discard a measurement sample where a cell is in a sleep state and provide an input to an L3 filter such that the absence of a measurement sample is not treated as bad measurement sample.

In another embodiment, a neighbouring cell can broadcast an indication that the cell is about to enter or has entered a sleep mode at the time of reference signal transmission occasions (as in Example 2 above or before the start of sleep period where SSB is off as in Example 1). At the reference signal transmission occasions, the cell transmits SS/PBCH for measurement purpose. Hence, for example a 1-bit field in a PBCH indicates that the cell is going to sleep mode. Remaining parameters, such as a duration of a sleep state, are provided from a serving or source cell. As a result, when a UE receives this signal from a neighbouring cell, the UE is informed that the cell is going to sleep for some time from that point onwards. The period may be fixed in specifications or provided from the serving cell.

In another embodiment, a base station (gNB) may modify SSB/CSI-RS to indicate that the cell is entering into a sleep mode, either during or before the start of its sleep period. A UE receiving a change in RS type can therefore receive an implicit indication that a cell is either in sleep mode or about to enter sleep mode.

In another embodiment, paging can be used from either a source cell or a target cell (if UE is capable of receiving paging from the target cell) when a cell enters a sleep mode. If paging is sent from the source cell then the paging message can include a target cell id and its NES state indication (for example 1-bit to indicate NES state is ON or OFF). The paging message could be a radio access network (RAN) paging message, for example one initiated by a RAN node and received by UEs when in all RRC states (e.g., IDLE, INACTIVE and CONNECTED states) where normally UE would measure SSB. CSI-RS based RRM measurements are usually performed in connected mode.

Example processes performed by a source infrastructure equipment and a communications device according to example embodiments are shown in Figures 7 and 8 respectively. Figure 7 shows a method of operating a source infrastructure equipment of a wireless communications network in a conditional handover in accordance with example embodiments. The method starts in step SI.

After step SI, in step S2, the method comprises configuring one or more conditions for triggering a handover of a communications device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communications network.

After step S2, in step S3, the method comprises transmitting, to the communications device, an indication of the one or more conditions for triggering the handover of the communications device from the source cell to the target cell. For example, the source infrastructure equipment may transmit a conditional handover configuration message comprising the one or more conditions for triggering the handover. The conditional handover message may be transmitted as an RRC signal, for example.

After step S3, in step S4, the method comprises determining that at least one of a source or serving cell in which the UE is currently communicating and one or more neighbouring cells which are being evaluated to be a target cell for handover has, or is expected to, enter a sleep state. In the sleep state the serving or one or more of the neighbouring cells will not be transmitting signals such as a PBCH (SSB) or CSI-RS from which measurements of signal quality of the cell cannot be received and evaluated.

After step S4, in step S5, the method comprises, in response, transmitting an indication to the communications device of a sleep state of the source or serving cell or one or more of the neighbouring cells has or will enter a sleep state. The communications device is therefore able to adapt an evaluation of a signal quality from the source or the one or more neighbouring cells to identify the source and target for a CHO.

In some embodiments, the indication of the sleep state according to the NES mode may be indicating by transmitting a Medium Access Control, MAC, signal dedicated for the communications device.

In some embodiments, the indication may be a MAC, Control Element, CE, signal.

The method ends in step S6.

A method of operating a communications device in a conditional handover in accordance with example embodiments is shown in Figure 8. The method starts in step Si l.

After step Si l, in step S12, the method comprises receiving, from source infrastructure equipment of a wireless communications network, one or more conditions for triggering a handover of the communications device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communications network.

After step S12, in step S13, the method comprises receiving, from the source infrastructure equipment, an evaluation trigger signal indicating to the communications device to evaluate one or more of the conditions for triggering the handover of the communications device from the source cell to the target cell. The evaluation trigger signal is received by the communications device from the source infrastructure equipment.

After step SI 3, in step S14, the method comprises receiving an indication that one or more of a source or serving cell and one or more neighbouring cells has or will enter a sleep state of an NES mode.

After step S14, in step S15, the method comprises evaluating one or more of the conditions. Using the indication received in step S 14, the communications device adapts a measurement evaluation of a signal quality of signals received from the cell concerned by not including evaluated samples of received signals which would have been transmitted in the sleep state. The communications device may also lengthen a period over which the measurement evaluation occurs.

After step S15, in step S16, the method comprises determining that one or more of the evaluated conditions have been met.

After step SI 6, in step SI 7, the method comprises, in response, initiating the handover of the communications device from the source cell to the target cell.

The initiation of the handover may involve detaching from a wireless access interface or radio link provided by the source infrastructure equipment and attaching to a wireless access interface or radio link provided by the target infrastructure equipment. The initiation of the handover may include establishing a wireless connection with the target relay infrastructure equipment. For example, the communications device may initiate an access procedure with the target infrastructure equipment. In one example, the communications device may initiate a Random Access Channel (RACH) procedure with the target infrastructure equipment.

The method ends in step SI 8.

As will be appreciated from the above explanation embodiments can provide a method of operating an infrastructure equipment of a wireless communications network forming a cell serving one or more communications devices. The method comprises transmitting via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, determining that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and transmitting an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

In some embodiments, the infrastructure equipment may be configured to transmit an indication that one or more neighbouring infrastructure equipment forming one or more neighbouring cells has or will enter a sleep state during which one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the one or more neighbouring cells cannot be made.

For an example application of conditional handover, the serving infrastructure equipment maybe a source infrastructure equipment and one of one or more neighbouring infrastructure equipment is a target infrastructure equipment for a conditional handover process performed a communications device, the target infrastructure equipment being identified by evaluating a quality of signals by measuring reference signals received from the source infrastructure equipment and the one or more neighbouring infrastructure equipment. The indication that one or more the source infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state to the communications device is used by the communications device in adjusting an evaluation of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

It will be appreciated that while the present disclosure has in some respects focused on implementations in an LTE-based and / or 5G network for the sake of providing specific examples, the same principles can be applied to other wireless telecommunications systems. Thus, even though the terminology used herein is generally the same or similar to that of the LTE and 5G standards, the teachings are not limited to the present versions of LTE and 5G and could apply equally to any appropriate arrangement not based on LTE or 5G and / or compliant with any other future version of an LTE, 5G or other standard.

It may be noted various example approaches discussed herein may rely on information which is predetermined / predefined in the sense of being known by both the base station and the communications device. It will be appreciated such predetermined / predefined information may in general be established, for example, by definition in an operating standard for the wireless telecommunication system, or in previously exchanged signalling between the base station and communications devices, for example in system information signalling, or in association with radio resource control setup signalling, or in information stored in a SIM application. That is to say, the specific manner in which the relevant predefined information is established and shared between the various elements of the wireless telecommunications system is not of primary significance to the principles of operation described herein. It may further be noted various example approaches discussed herein rely on information which is exchanged / communicated between various elements of the wireless telecommunications system and it will be appreciated such communications may in general be made in accordance with conventional techniques, for example in terms of specific signalling protocols and the type of communication channel used, unless the context demands otherwise. That is to say, the specific manner in which the relevant information is exchanged between the various elements of the wireless telecommunications system is not of primary significance to the principles of operation described herein.

It will be appreciated that the principles described herein are not applicable only to certain types of communications device, but can be applied more generally in respect of any types of communications device, for example the approaches are not limited to URLLC / IIoT devices or other low latency communications devices, but can be applied more generally, for example in respect of any type of communications device operating with a wireless link to the communication network.

It will further be appreciated that the principles described herein are applicable not only to LTE-based or 5G/NR-based wireless telecommunications systems, but are applicable for any type of wireless telecommunications system that supports a dynamic scheduling of shared communications resources.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting of the scope of the invention, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, define, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

Respective features of the present disclosure are defined by the following numbered paragraphs:

Paragraph 1. A method of operating a communications device in a wireless communications network, the method comprising measuring signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, evaluating the signal measurements as part of a process performed by the communications device, receiving an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and the evaluating the signal measurements, adjusting the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

Paragraph 2. A method of paragraph 1, wherein the adjusting the evaluation of the signal measurements comprises discounting signal measurements of signals which would have been received for measurement evaluation during the sleep state of the one or more of the serving cell and the one or more neighbouring cells.

Paragraph 3. A method of paragraph 1, wherein the adjusting the evaluation of the signal measurements comprises increasing a period over the signal measurements are performed with respect to a period for performing the evaluation for a cell which is not in sleep state.

Paragraph 4. A method of any of paragraphs 1, 2 or 3, wherein the indication that the one or more of the serving infrastructure equipment of the serving cell and the one or more of the neighbouring infrastructure equipment of the neighbouring cells has or will enter a sleep state, comprises signalling the sleep state as part of a NES mode sleep cycle. Paragraph 5. A method of paragraph 4, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

Paragraph 6. A method of paragraph 5, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

Paragraph 7. A method of paragraph 6, wherein the MAC signalling comprises a MAC-CE.

Paragraph 8. A method of any of paragraphs 4 to 7, wherein the signalling indicates a start and an end of a sleep state of one or more the source infrastructure equipment and the one or more of the neighbouring infrastructure equipment is about to enter a sleep state.

Paragraph 9. A method of any of paragraphs 4 to 7, wherein the signalling indicates that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment is about to enter a sleep state.

Paragraph 10. A method of any of paragraphs 1, 2 or 3, wherein the receiving the indication that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication from a signal being measured from the one or more of the serving infrastructure equipment and the one or more of the neighbouring infrastructure equipment. Paragraph 11. A method of paragraph 10, wherein the signal being measured is one of a physical broadcast channel, PBCH, or a channel state information reference signal, CSI-RS.

Paragraph 12. A method of any of paragraphs 1, 2 or 3, wherein the receiving the indication that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication as a paging message.

Paragraph 13. A method of any of paragraphs 1 to 12, wherein the receiving the indication that the one or more of the source infrastructure equipment and the one or more of the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication from the source infrastructure equipment.

Paragraph 14. A method of any of paragraphs 1 to 13, wherein the process performed by the communications device for which the signal measurements are performed and evaluated is part of a conditional handover process, the serving infrastructure equipment of the serving cell being a source infrastructure equipment and the one or more neighbouring cells provided by the neighbouring infrastructure equipment are evaluated to identify a target infrastructure equipment for handover, and the method comprises receiving, from the serving infrastructure equipment, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from the one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and the adjusting the evaluation of the signal measurements comprises adjusting the evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

Paragraph 15. A method of paragraph 14, wherein a period over which the evaluation of the signal measurements are perform is a SSB-based radio resource measurement, RRM, Measurement Timing Configuration, SMTC, window.

Paragraph 16. A method of operating an infrastructure equipment of a wireless communications network forming a cell serving one or more communications devices, the method comprising transmitting via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, determining that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and transmiting an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

Paragraph 17. A method of paragraph 16, wherein the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmiting the indication of the sleep state as part of aNES mode sleep cycle.

Paragraph 18. A method of paragraph 17, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

Paragraph 19. A method of paragraph 17, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

Paragraph 20. A method of paragraph 19, wherein the MAC signalling comprises a MAC-CE.

Paragraph 21. A method of any of paragraphs 16 to 20, wherein the indication indicates a start and an end of a sleep state of the serving infrastructure equipment.

Paragraph 22. A method of any of paragraphs 16 to 21, wherein the signalling indicates that the serving infrastructure equipment is about to enter a sleep state.

Paragraph 23. A method of any of paragraphs 16 to 22, wherein the transmiting the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmiting the indication from a reference signal being used to evaluate signals measured from the serving infrastructure equipment.

Paragraph 24. A method of paragraph 23, wherein the reference signal being measured is one of a physical broadcast channel, PBCH, or a channel state information reference signal, CSI-RS.

Paragraph 25. A method of any of paragraphs 16 to 22, wherein the transmiting the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmiting the indication as a paging message.

Paragraph 26. A method of any of paragraphs 16 to 25, wherein the transmiting the indication that the serving infrastructure equipment has or will enter a sleep state includes transmiting an indication that one or more neighbouring infrastructure equipment forming one or more neighbouring cells has or will enter a sleep state during which one or more reference signals will not be transmited and signal measurements for evaluating the signal quality of the one or more neighbouring cells cannot be made.

Paragraph 27. A method of paragraph 26, comprising receiving an indication that one or more of the one or more of the neighbouring infrastructure equipment has or will enter a sleep state, and the transmiting the indication comprises transmiting the indication that one or more of the neighbouring infrastructure equipment has or will enter a sleep state.

Paragraph 28. A method of paragraph 27, wherein the indication is received from an Xn interface from the one or more of the neighbouring infrastructure equipment.

Paragraph 29. A method of any of paragraphs 26, 27 or 28, wherein the indication that one or more of the neighbouring infrastructure equipment has or will enter a sleep state, comprises transmiting the indication of the sleep state as part of a NES mode sleep cycle of the neighbouring infrastructure equipment.

Paragraph 30. A method of paragraph 29, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

Paragraph 31. A method of paragraph 29, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

Paragraph 32. A method of paragraph 31, wherein the MAC signalling comprises a MAC-CE.

Paragraph 33. A method of any of paragraphs 26 to 32, wherein the indication indicates a start and an end of a sleep state of each of the one or more neighbouring infrastructure equipment. Paragraph 34. A method of any of paragraphs 26 to 33, wherein the signalling indicates that each of the one or more neighbouring infrastructure equipment is about to enter a sleep state.

Paragraph 35. A method of any of paragraphs 26 to 32, wherein the serving infrastructure equipment is a source infrastructure equipment and one of the one or more neighbouring infrastructure equipment is a target infrastructure equipment for a conditional handover process performed by at least one of the one or more communications devices, the target infrastructure equipment being identified by evaluating a quality of signals by measuring reference signals received from the source infrastructure equipment and the one or more neighbouring infrastructure equipment, the indication that one or more the source infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state to the communications device being used by the communications device in adjusting an evaluation of the one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

Paragraph 36. A method of paragraph 35, comprising configuring one or more conditions for triggering a handover of a communications device from the source cell to a target cell provided by the target infrastructure equipment of the wireless communications network, the target infrastructure equipment being identified from one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and transmitting, to the communications device, an indication of the one or more conditions for triggering the handover of the communications device from the source cell to the target cell,

Paragraph 37. A communications device configured to transmit data via a wireless communications network, the communications device comprising transceiver circuitry configured to transmit signals to or to receive signals from an infrastructure equipment via a wireless access interface provided by the wireless communications network, and controller circuitry configured to control the transceiver circuitry to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

Paragraph 38. A communications device of paragraph 37, wherein the process performed by the communications device for which the signal measurements are performed and evaluated is part of a conditional handover process, the serving infrastructure of the serving cell being a source infrastructure equipment and the one or more neighbouring cells provided by the neighbouring infrastructure equipment are evaluated to identify a target infrastructure equipment for handover, the controller circuitry controls and the transceiver circuitry to receive, from the serving infrastructure equipment, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from the one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and to adjust the evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

Paragraph 39. An infrastructure equipment for forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to or to receive signals from communications devices via a wireless access interface provided by the infrastructure equipment, and controller circuitry configured to control the transceiver circuitry to transmit via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, to determine that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and to transmit an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

Paragraph 40. An infrastructure equipment of paragraph 39, wherein the controller circuitry controls and the transceiver circuitry to transmit an indication that one or more neighbouring infrastructure equipment forming one or more neighbouring cells has or will enter a sleep state during which one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the one or more neighbouring cells cannot be made.

Paragraph 41. An infrastructure equipment of paragraph 39 or 40, wherein the serving infrastructure equipment is a source infrastructure equipment and one of the one or more neighbouring infrastructure equipment is a target infrastructure equipment for a conditional handover process performed by at least one of the one or more communications devices, the target infrastructure equipment being identified by evaluating a quality of signals by measuring reference signals received from the source infrastructure equipment and the one or more neighbouring infrastructure equipment, the indication that one or more the source infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state to the communications device being used by the communications device in adjusting an evaluation of the one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

Paragraph 42. Circuitry for a communications device configured to transmit data via a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to or to receive signals from an infrastructure equipment via a wireless access interface provided by the wireless communications network, and controller circuitry configured to control the transceiver circuitry to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

Paragraph 43. Circuitry for an infrastructure equipment for forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to or to receive signals from communications devices via a wireless access interface provided by the infrastructure equipment, and controller circuitry configured to control the transceiver circuitry to transmit via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, to determine that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and to transmit an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

Paragraph 44. A wireless communications network comprising a communications device according to paragraph 37 and infrastructure equipment according to paragraph 41.

Paragraph 45. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform the method of any of paragraphs 1 to 36.

Paragraph 46. A non-transitory computer-readable storage medium storing a computer program according to paragraph 45.

References

[1] RP-182090, “Revised SID: Study on NR Industrial Internet of Things (IoT),” 3GPP RAN#81.

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

[3] TS38.300 V16.5.0, “NG and NR-RAN Overall Description”, Release 16.

[4] RP -213554, “Study on network energy savings for NR”.

[5] TR38.840, “Study on User Equipment (UE) power saving in NR”, Release 16.

[6] TR38.864, “Study on network energy savings for NR”, Release 18.

[7] R2-2213040, “Post RAN2#120 TP for TR 38.864”, Release 18.

Claims

CLAIMS What is claimed is:

1. A method of operating a communications device in a wireless communications network, the method comprising measuring signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, evaluating the signal measurements as part of a process performed by the communications device, receiving an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and the evaluating the signal measurements, adjusting the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

2. A method of claim 1, wherein the adjusting the evaluation of the signal measurements comprises discounting signal measurements of signals which would have been received for measurement evaluation during the sleep state of the one or more of the serving cell and the one or more neighbouring cells.

3. A method of claim 1, wherein the adjusting the evaluation of the signal measurements comprises increasing a period over the signal measurements are performed with respect to a period for performing the evaluation for a cell which is not in sleep state.

4. A method of claim 1, wherein the indication that the one or more of the serving infrastructure equipment of the serving cell and the one or more of the neighbouring infrastructure equipment of the neighbouring cells has or will enter a sleep state, comprises signalling the sleep state as part of a NES mode sleep cycle.

5. A method of claim 4, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

6. A method of claim 5, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

7. A method of claim 6, wherein the MAC signalling comprises a MAC-CE.

8. A method of claim 4, wherein the signalling indicates a start and an end of a sleep state of one or more the source infrastructure equipment and the one or more of the neighbouring infrastructure equipment is about to enter a sleep state.

9. A method of claim 4, wherein the signalling indicates that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment is about to enter a sleep state.

10. A method of claim 1, wherein the receiving the indication that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication from a signal being measured from the one or more of the serving infrastructure equipment and the one or more of the neighbouring infrastructure equipment.

11. A method of claim 10, wherein the signal being measured is one of a physical broadcast channel, PBCH, or a channel state information reference signal, CSI-RS.

12. A method of claim 1, wherein the receiving the indication that the one or more of the serving infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication as a paging message.

13. A method of claim 1, wherein the receiving the indication that the one or more of the source infrastructure equipment and the one or more of the neighbouring infrastructure equipment has or will enter a sleep state, comprises receiving the indication from the source infrastructure equipment.

14. A method of claim 1, wherein the process performed by the communications device for which the signal measurements are performed and evaluated is part of a conditional handover process, the serving infrastructure equipment of the serving cell being a source infrastructure equipment and the one or more neighbouring cells provided by the neighbouring infrastructure equipment are evaluated to identify a target infrastructure equipment for handover, and the method comprises receiving, from the serving infrastructure equipment, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from the one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and the adjusting the evaluation of the signal measurements comprises adjusting the evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

15. A method of claim 14, wherein a period over which the evaluation of the signal measurements are perform is a S SB-based radio resource measurement, RRM, Measurement Timing Configuration, SMTC, window.

16. A method of operating an infrastructure equipment of a wireless communications network forming a cell serving one or more communications devices, the method comprising transmitting via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, determining that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and transmitting an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

17. A method of claims 16, wherein the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmitting the indication of the sleep state as part of aNES mode sleep cycle.

18. A method of claim 17, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

19. A method of claim 17, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

20. A method of claim 19, wherein the MAC signalling comprises a MAC-CE.

21. A method of claim 16, wherein the indication indicates a start and an end of a sleep state of the serving infrastructure equipment.

22. A method of claim 16, wherein the signalling indicates that the serving infrastructure equipment is about to enter a sleep state.

23. A method of claim 16, wherein the transmitting the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmitting the indication from a reference signal being used to evaluate signals measured from the serving infrastructure equipment.

24. A method of claim 23, wherein the reference signal being measured is one of a physical broadcast channel, PBCH, or a channel state information reference signal, CSI-RS.

25. A method of claim 16, wherein the transmitting the indication that the serving infrastructure equipment has or will enter a sleep state, comprises transmitting the indication as a paging message.

26. A method of claim 16, wherein the transmitting the indication that the serving infrastructure equipment has or will enter a sleep state includes transmitting an indication that one or more neighbouring infrastructure equipment forming one or more neighbouring cells has or will enter a sleep state during which one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the one or more neighbouring cells cannot be made.

27. A method of claim 26, comprising receiving an indication that one or more of the one or more of the neighbouring infrastructure equipment has or will enter a sleep state, and the transmitting the indication comprises transmitting the indication that one or more of the neighbouring infrastructure equipment has or will enter a sleep state.

28. A method of claim 27, wherein the indication is received from an Xn interface from the one or more of the neighbouring infrastructure equipment.

29. A method of claim 26, wherein the indication that one or more of the neighbouring infrastructure equipment has or will enter a sleep state, comprises transmitting the indication of the sleep state as part of a NES mode sleep cycle of the neighbouring infrastructure equipment.

30. A method of claim 29, wherein the NES mode sleep cycle is signalled using radio resource control, RRC, signalling.

31. A method of claim 29, wherein the NES mode sleep cycle is signalled using media access control, MAC, signalling.

32. A method of claim 31, wherein the MAC signalling comprises a MAC-CE.

33. A method of claim 26, wherein the indication indicates a start and an end of a sleep state of each of the one or more neighbouring infrastructure equipment.

34. A method of claim 26, wherein the signalling indicates that each of the one or more neighbouring infrastructure equipment is about to enter a sleep state.

35. A method of claim 26, wherein the serving infrastructure equipment is a source infrastructure equipment and one of the one or more neighbouring infrastructure equipment is a target infrastructure equipment for a conditional handover process performed by at least one of the one or more communications devices, the target infrastructure equipment being identified by evaluating a quality of signals by measuring reference signals received from the source infrastructure equipment and the one or more neighbouring infrastructure equipment, the indication that one or more the source infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state to the communications device being used by the communications device in adjusting an evaluation of the one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

36. A method of claim 35, comprising configuring one or more conditions for triggering a handover of a communications device from the source cell to a target cell provided by the target infrastructure equipment of the wireless communications network, the target infrastructure equipment being identified from one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and transmitting, to the communications device, an indication of the one or more conditions for triggering the handover of the communications device from the source cell to the target cell,

37. A communications device configured to transmit data via a wireless communications network, the communications device comprising transceiver circuitry configured to transmit signals to or to receive signals from an infrastructure equipment via a wireless access interface provided by the wireless communications network, and controller circuitry configured to control the transceiver circuitry to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

38. A communications device of claim 37, wherein the process performed by the communications device for which the signal measurements are performed and evaluated is part of a conditional handover process, the serving infrastructure of the serving cell being a source infrastructure equipment and the one or more neighbouring cells provided by the neighbouring infrastructure equipment are evaluated to identify a target infrastructure equipment for handover, the controller circuitry controls and the transceiver circuitry to receive, from the serving infrastructure equipment, an indication of one or more conditions for triggering a handover of the communications device from the source cell to a target cell provided by a target infrastructure of the wireless communications network, the target infrastructure equipment being identified from the one or more neighbouring infrastructure equipment providing the one or more neighbouring cells, and to adjust the evaluation of signal measurements from one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

39. An infrastructure equipment for forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to or to receive signals from communications devices via a wireless access interface provided by the infrastructure equipment, and controller circuitry configured to control the transceiver circuitry to transmit via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, to determine that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and to transmit an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

40. An infrastructure equipment of claim 39, wherein the controller circuitry controls and the transceiver circuitry to transmit an indication that one or more neighbouring infrastructure equipment forming one or more neighbouring cells has or will enter a sleep state during which one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the one or more neighbouring cells cannot be made.

41. An infrastructure equipment of claim 39, wherein the serving infrastructure equipment is a source infrastructure equipment and one of the one or more neighbouring infrastructure equipment is a target infrastructure equipment for a conditional handover process performed by at least one of the one or more communications devices, the target infrastructure equipment being identified by evaluating a quality of signals by measuring reference signals received from the source infrastructure equipment and the one or more neighbouring infrastructure equipment, the indication that one or more the source infrastructure equipment and the neighbouring infrastructure equipment has or will enter a sleep state to the communications device being used by the communications device in adjusting an evaluation of the one or more of the source cell and the one or more neighbouring cells based on the indication for determining the one or more conditions for triggering conditional handover.

42. Circuitry for a communications device configured to transmit data via a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to or to receive signals from an infrastructure equipment via a wireless access interface provided by the wireless communications network, and controller circuitry configured to control the transceiver circuitry to measure signals received from an infrastructure equipment of a cell serving the communications device and one or more other infrastructure equipment forming cells neighbouring the serving cell, to evaluate the signal measurements as part of a process performed by the communications device, to receive an indication that one or more of the infrastructure equipment of the serving cell and the one or more infrastructure equipment of the neighbouring cells has or will enter a sleep state, and to adjust the evaluation of the signal measurements from the one or more infrastructure equipment of the serving cell and the one or more neighbouring cells based on the indication.

43. Circuitry for an infrastructure equipment for forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to or to receive signals from communications devices via a wireless access interface provided by the infrastructure equipment, and controller circuitry configured to control the transceiver circuitry to transmit via a wireless access interface formed by the serving infrastructure equipment, in the serving cell, one or more reference signals for measuring a quality of signals received by the one or more communications devices in the serving cell by detecting and measuring the reference signals, to determine that the infrastructure equipment has or will enter a sleep state in which the one or more reference signals will not be transmitted and signal measurements for evaluating the signal quality of the serving cell cannot be made, and to transmit an indication that the infrastructure equipment has or will enter a sleep state to the one or more communications devices, for use by the one or more communications device in adjusting an evaluation of the one or more of the serving cell.

44. A wireless communications network comprising a communications device according to claim 37 and infrastructure equipment according to claim 41.

45. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform the method of claim 1 or claim 16.

46. A non-transitory computer-readable storage medium storing a computer program according to claim 45.