Methods, distributed units, and central units of wirleess communications networks

Abstract

A method of operating a distributed unit, DU, of a wireless communications network is provided. The method comprises determining that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, determining that the at least one first preconfigured condition has been met, and transmitting, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

Description

[0001] METHODS, DISTRIBUTED UNITS, AND CENTRAL UNITS OF WIRLEESS COMMUNICATIONS NETWORKS

[0002] BACKGROUND Field of Disclosure

[0003] The present disclosure relates to distributed units (DUs) and central units (CUs) of wireless communications networks and methods of operating such DUs and CUs to allow for more efficient and effective network energy saving.

[0004] The present application claims the Paris Convention priority from European patent application number EP23202205.3, filed on 6 October 2023, the contents of which are hereby incorporated by reference.

[0005] Description of Related Art

[0006] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

[0007] Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

[0008] Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different consideration may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

[0009] In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements. The desire to support these new use-cases and scenarios gives rise to new challenges for efficiently handling communications in wireless communications systems that need to be addressed.

[0010] SUMMARY OF THE DISCLOSURE

[0011] The present disclosure can help address or mitigate at least some of the issues discussed above.

[0012] At least some embodiments of the present technique can provide a method of operating a distributed unit, DU, of a wireless communications network. The method comprises determining that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, determining that the at least one first preconfigured condition has been met, and transmitting, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

[0013] At least some embodiments of the present technique can provide a method of operating a distributed unit, DU, of a wireless communications network. The method comprises receiving, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and receiving, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0014] Such embodiments of the present technique, which, in addition to methods of operating DUs, relate to methods of operating central units (CUs) of wireless communications networks, to DUs and CUs, to circuitry for DUs and CUs, to wireless communications systems, to computer programs, and to computer- readable storage mediums, can allow for more efficient and effective network energy saving.

[0015] Respective aspects and features of the present disclosure are defined in the appended claims.

[0016] 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.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

[0019] 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;

[0020] Figure 2 schematically represents some aspects of an NR-type wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure; Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0021] Figure 4A is a representation of a gNB distributed unit (DU) and a gNB controlling unit (CU) communicating via an Fl interface;

[0022] Figure 4B is a schematic representation of a protocol stack operated respectively by the gNB DU and gNB CU shown in Figure 4A for communicating control plane data;

[0023] Figure 4C is a schematic representation of a protocol stack operated respectively by the gNB DU and gNB CU shown in Figure 4 A for communicating user plane data;

[0024] Figure 5 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

[0025] Figure 6 is reproduced from [3], and illustrates successful operation of the gNB-central unit (gNB-CU) configuration update procedure;

[0026] Figure 7 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with embodiments of the present technique;

[0027] Figure 8 shows a flow diagram illustrating a second example process of communications in a communications system in accordance with embodiments of the present technique; and Figure 9 shows a flow diagram illustrating a third example process of communications in a communications system in accordance with embodiments of the present technique.

[0028] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Long Term Evolution Advanced Radio Access Technology (4G)

[0030] Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Holma H. and Toskala A [1], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

[0031] The network 6 includes a plurality of base stations 1 connected to a core network 2, which may be for example an Evolved Packet Core (EPC). Each base station provides a coverage area 3 (i.e., a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network.

[0032] Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e., page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

[0033] Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, eNodeBs, eNB, gNodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

[0034] New Radio Access Technology (5G)

[0035] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the DUs 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 (which may be for example referred to as 5GC) which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 30.

[0036] The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

[0037] The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network. In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

[0038] It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

[0039] Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0040] A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

[0041] The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G / NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

[0042] As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

[0043] The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with 3GPP technical specifications [2] and [3], and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

[0044] As will be appreciated by those acquainted with 5G architecture, the CU 40 may be a logical node which hosts Radio Resource Control (RRC) protocols, Service Data Adaptation Protocols (SDAP), and Packet Data Convergence Protocols (PDCP) of a gNB. Alternatively, the CU 40 may be a logical node which hosts RRC and PDCP protocols of an en-gNB (which is a gNB that is able to connect with both EPC and eNBs and can be understood as being, for example, a secondary node (SgNB) used in dual connectivity scenarios). The CU 40 partly controls the operation of one or more DUs 40 and terminates the Fl interface 46 for the DUs that it controls. The DU 42 may be a logical node which hosts Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of a gNB or en-gNB. The operation of the DU 42 is partly controlled by the CU 40 for which the DU 42 terminates the Fl interface 46.

[0045] Although not shown in Figures 2 or 3, it will be familiar to those acquainted with 5G architecture that the CU 40 may be further split into a CU-CP which performs the control plane functions of the CU 40 and a CU-UP which performs the user plane functions of the CU 40 (see for example, [4]). In more detail, the CU-CP may be a logical node hosting an RRC protocol and a control plane part of a PDCP protocol of the CU 40 for the gNB or en-gNB. The CU-CP terminates an El interface connected with the CU-UP and an Fl-C interface connected with the DU 42. As will be appreciated, the Fl-C interface carries control plane signalling of the Fl interface 46. The CU-UP may be a logical node which hosts a user plane part of a PDCP protocol of the CU 40 for an en-gNB. Alternatively, the CU-UP may be a logical node which hosts a user plane part of the PDCP protocol and an SDAP protocol of the CU 40 for a gNB. The CU-UP terminates an El interface connected with the CU-CP and an Fl-U interface connected with the DU 42. As will be appreciated, the Fl-U interface carries user plane signalling of the Fl interface 46. In order to appreciate example embodiments, a protocol stack for forming a conventional Fl interface shown in Figure 2 and 3 will be explained with reference to Figures 4A, 4B, and 4C. In respect of a protocol stack, Figures 4A, 4B, and 4C provide an illustration of processing performed by the elements shown in Figures 2 and 3 which form the packet data communications path 46 between the gNB-DU 42 and the gNB-CU 40 via the Fl interface 46. Control plane communications are considered separately to user plane data, although in practice they form the same interface and are processed and transmitted by the same hardware equipment.

[0046] As shown in Figure 4A, communication is formed between the gNB DU 42 and a gNB CU 40 for the Fl interface 46. However, the control plane protocol stack to form this interface is shown in Figure 4B, and the user plane protocol stack for communicating the user data between the gNB-CU 40 and gNB-DU 42 is shown in Figure 4C. As shown in Figure 4B, at the radio network layer, the control plane is formed by Fl Application Protocols (FlAPs) 301a in the gNB-CU 40 and by Fl APs 301b in the gNB DU 42. As will be understood by those acquainted with the 5G Architecture, communication between a gNB-CU and a gNB DU is by IPv6 or IPv4 Internet protocols as specified in [5], This is shown in Figure 4B as an IP layer 302a in the gNB-CU 40 and an IP layer 302b in the gNB-DU 42, forming an IP communication interface 302c. A Stream Control Transmission Protocol (SCTP) layer of the protocol stack 304a, 304b, 304c controls end to end communication via the IP layer 302 including flow control and quality of service. The IP data is communicated between the gNB DU and gNB CU via logical data link layer 306a, 306b, 306c and the physical layer 308a, 308b, 308c.

[0047] In the user plane, the radio network layer is formed by RLC layer 320a, 320b to form the Fl interface for communicating use plane data 46. The protocol stack in the transport layer comprises a General Packet Ratio Service (GPRS) Tunnelling Protocol for user plane data (GTP-U) 322a, 322b, 322c, which controls communication of user plane data for roaming and home subscribers via a UDP layer 324a, 324b, 324c which controls communication of user plane data via an IP layer 326a, 326b, 326c. As with the control plane, the IP data is communicated between the gNB DU and gNB CU via logical data link layer 328a, 328b, 328c and the physical layer 330a, 330b, 330c.

[0048] CU-DU Split Functions

[0049] As indicated above, the CU 40 and DU 42 are configured to execute gNB functionality. The allocation or splitting of gNB functions between the CU 40 and the DU 42 is discussed in [6] . Such gNB functions include:

[0050] • Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);

[0051] • IP and Ethernet header compression, encryption and integrity protection of data;

[0052] • Selection of an Access and Mobility Management Function (AMF) at UE attachment when no routing to an AMF can be determined from the information provided by the UE;

[0053] • Routing of User Plane data towards User Plane Functions (UPFs);

[0054] • Routing of Control Plane information towards AMF;

[0055] • Connection setup and release;

[0056] • Scheduling and transmission of paging messages;

[0057] • Scheduling and transmission of system broadcast information (originated from the AMF or 0AM);

[0058] • Measurement and measurement reporting configuration for mobility and scheduling;

[0059] • Transport level packet marking in the uplink; • Session Management;

[0060] • Support of Network Slicing;

[0061] • QoS Flow management and mapping to data radio bearers;

[0062] • Support of UEs in RRC INACTIVE state;

[0063] • Distribution function for NAS messages;

[0064] • Radio access network sharing;

[0065] • Dual Connectivity;

[0066] • Tight interworking between NR and E-UTRA; and

[0067] • Maintain security and radio configuration for User Plane Cellular Internet of Things (CIoT) 5GS Optimisation, as defined in [7] (ng-eNB only).

[0068] All functions listed above, except for the final function, can be performed by gNBs and ng-eNBs while the final function relating to the maintenance of security and radio configurations is performed by ng- eNBs only. As those skilled in the art would understand, an ng-eNB is an eNB which connects 5G UEs to the 5G core network using 4G LTE air interface. Furthermore, bandwidth reduced low complexity (BL) UEs or UEs in enhanced coverage are only supported by ng-eNBs (see, for example, [6]). Additionally, NB-IoT UE is only supported by ng-eNBs (see, for example, [6]).

[0069] Network Energy Saving (NES)

[0070] In Release- 18 of the 3GPP standards, a new study item [8] was initiated on Network Energy Saving (NES). The objectives of the study item are the following:

[0071] (i) Defining a base station energy consumption model;

[0072] (ii) Defining of an evaluation methodology and Key Performance Indicators (KPIs); and

[0073] (iii) Identifying techniques on the gNB and UE side to improve network energy savings in terms of both base station transmission and reception.

[0074] Objective (i) is expected to include adapting frameworks of power consumption modelling and evaluation methodologies for UE power saving in NR (discussed in [9]) 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.

[0075] 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.

[0076] 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 [8] is expected to prioritise 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.

[0077] The following examples of single-carrier and multi-carrier deployments are expected to be prioritised in the study item:

[0078] • Urban micro in FR1, including Time Division Duplex (TDD) massive Multiple-Input Multiple- Output (MIMO). This can also model small cells;

[0079] • FR2 beam-based scenarios (note: this scenario can also model small cells);

[0080] • Urban / Rural macro in FR1 with / without DSS Dynamic Spectrum Sharing (DSS). No impact to LTE expected in case of DSS; and

[0081] • 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.

[0082] 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.

[0083] NES Modes

[0084] 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 (which is reproduced from

[0010] ) illustrates examples of proposed NES modes.

[0085] Table 1. Proposed NES modes

[0086] 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.

[0087] Table 2 (reproduced from [7]) 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 [7] .

[0088] 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 data transmissions. As will be understood by one skilled in the art, a communications device in a cell in an OFF NES mode may still receive reference signals or send wakeup signal to wake up the cell. It would also be appreciated by those skilled in the art that a NES cell is a cell that is able to support NES technologies and configurations, but which does not necessarily have to be operating in accordance with a NES mode (such as those described herein) at all times.

[0089] 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.

[0090] Artificial intelligence (AI) / machine learning (ML) for the New Generation (i.e. 5G) Radio Access Network (NG-RAN) is discussed in

[0011] , which lists as its objectives the specification of data collection enhancements and signalling support within existing NG-RAN interfaces and architecture (including nonsplit architecture and split architecture) for AI / ML-based NES, load balancing and mobility optimisation. In view of this, it is considered highly likely at the time of filing of the present disclosure that NES will be further enhanced in Release-19 of the 3GPP standards.

[0091] With the existing CU-DU architecture, as described above with reference to Figure 3, and Figures 4A, 4B, and 4C, the decision in respect of which cells should enter into the sleep state or move back into the ON state is made by the CU. The DU may need to send assistance information (e.g. cell load, cell energy consumption status, etc.) to the CU in order to assist the CU in making any energy saving decisions. This feedback-decision-configuration procedure will prolong the decision-making time, and as a result will compromise the network energy saving performance level. This is especially the case as it is always necessary for the DU to have the up-to-date cell level information to be able to provide to the CU, and it may possibly be the case in the future that feedback from UEs to the network regarding the network energy saving performance will be introduced. Therefore, it is proposed that signalling that can enable and allow the DU to itself make cell sleep / wake-up decisions without being instructed to do so by the CU should be introduced, in order to make such decisions more time and power efficient.

[0092] Some proposals for such signalling are discussed in

[0012] and

[0013] , for example. In

[0012] , it is proposed that gNB-DU assisted / initiated cell (de)activation be supported. It is understood that this proposal supports the DU sending NES-related assistance information to the CU, in order for the CU to allow the CU to re-configure a cell list for further (de)activation. In

[0013] , it is proposed that the CU configures a cell list for the DU, and DU is then able to make decisions, based on this configured cell list, in respect of which cells to (de)activate.

[0093] However, as those skilled in the art would appreciate, in order to make such decisions on cell (de)activation and / or to transmit assistance information as time and power efficient as possible, the DU needs to know the conditions under which it should (de)activate such cells and / or transmit such assistance information. The proposals of both

[0012] and

[0013] are silent in respect of such conditions. Embodiments of the present technique therefore seek to provide solutions for the more efficient and effective cell (de)activation decisions.

[0094] Cell Sleep Signalling to Support Fast Cell Deactivation for NES Cells

[0095] Figure 5 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a first infrastructure equipment (e.g. gNB-DU) 51, and a second infrastructure equipment (e.g. gNB-CU) 52 in accordance with at least some embodiments of the present technique. Here, the first infrastructure equipment 51 may be a distributed unit, DU, of a wireless communications network (i.e. a gNB-DU) and the second infrastructure equipment 52 may be a central unit, CU, of the wireless communications network (i.e. a gNB-CU), and can be understood with reference to Figures 4A, 4B, and 4C as described above. Here, the DU 51 may control one or more cells (which may be, for example, NES cells). Each of these cells may serve one or more UEs, which may be NES UEs; i.e. UEs that are able to support functions of an NES cell, and thus is able to connect to such NES cells. The DU 51 may support one or more beams for transmitting signals to and / or receiving signals from one or more UEs located in the cells served by the DU 51. These beams may be referred to as NES beams (i.e. beams used for communications with NES cells, where the NES beams may be controlled by the NES cells themselves, and where an NES cell is switched on or off, its associated NES beams may also be switched on or off). The first infrastructure equipment (e.g. gNB-DU) 51 and the second infrastructure equipment (e.g. gNB-CU) 52 each comprise a transceiver (or transceiver circuitry) 51.1, 52. 1, and a controller (or controller circuitry) 51.2, 52.2. Each of the controllers 51.2, 52.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

[0096] As shown in the example of Figure 5, the transceiver circuitry 51.1 and the controller circuitry 51.2 of the DU (i.e. the first infrastructure equipment) 51 are configured in combination to determine 53 that the DU 51 is to transmit assistance information to the CU (i.e. the second infrastructure equipment) 52 upon at least one first preconfigured condition being met (e.g. through receipt of a request 60 to transmit said assistance information from the CU 52), wherein the assistance information is associated with at least one NES cell and / or at least one NES beam associated with the DU 51 and may also be received (separately from or together with the request 60 to transmit the assistance information) from the CU 51, to determine 54 that the at least one first preconfigured condition has been met, and to transmit 55, to the CU 52 upon determining 54 that the at least one first preconfigured condition has been met, the assistance information. The transceiver circuitry 51.1 and the controller circuitry 51.2 of the DU 51 may then further be configured to receive 56, from the CU 52, an indication of a list of one or NES cells and / or one or more NES beams associated with the DU 51, and to receive 57, from the CU 52, an indication of at least one second preconfigured condition in accordance with which the DU 51 is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state. The transceiver circuitry 51.1 and the controller circuitry 51.2 of the DU 51 may then later be configured to determine 58 that the at least one second preconfigured condition has been met for at least one of the NES cells and / or NES beams on the indicated list, and to switch 59, upon determining 58 that the at least one second preconfigured condition has been met for the at least one of the NES cells and / or NES beams, the at least one of the NES cells and / or NES beams from the on state to the energy saving state or from the energy saving state to the on state.

[0097] Essentially, such embodiments of the present technique as exemplified by Figure 5 propose that the CU configures the DU to report NES-related assistance information (for cells and / or beams that it serves) and that this report will be sent when pre-configured conditions are met. Separately, or in addition, such embodiments of the present technique as exemplified by Figure 5 propose that the CU configures the DU with a list of cells / beams which are potentially candidates to switch off (and / or switch on), together with the conditions that need to be fulfilled in order for the DU to switch them off (and / or on). Following the transmission of this list (and conditions), it is up to the DU to decide which cells / beams to switch off, and when, according to the status of the cells / beams. Here, this status of the cells / beams includes, but is not limited to, the current traffic load of those cells / beams, the power consumption of those cells / beams, the energy efficiency of those cells / beams, the resource utilisation of those cells / beams, or whether any of those cells (or beams) are mutually exclusive with another cell (or beam) in respect of when they are allowed to be switched off.

[0098] Embodiments of the present technique therefore enable the DU rather than the CU to make cell (or beam) activation / deactivation decisions, which allows for the saving of time, signalling, and power as the CU does not need to be involved in the decision making. The only signalling required is the indication from the CU to the DU of the list of NES cells / beams that the DU is able to switch on or off, and / or the indication of the NES-related assistance information by the DU to the CU, where such assistance information may be used by the CU to determine and form the list of NES cells / beams that the DU is able to switch on or off. The requirement for preconfigured conditions to be met to trigger the DU to transmit the assistance information and / or switch the NES cells / beams on the list on / off is something not envisaged by the solutions proposed in either

[0012] or

[0013] , and ensures that the transmission of the assistance information and / or NES cells / beams are switched on / off by the DU in a quicker, more efficient, and proper manner.

[0099] In [3], the gNB-CU configuration update - to update the (CU) configuration at the gNB-DU - is introduced. The procedure for this gNB-CU configuration update is shown in Figure 6, which is reproduced from [3], Here, the procedure shown in Figure 6 is a procedure where the gNB-DU is provided with the updated gNB-CU configuration is updated successfully. Firstly, the gNB-DU 61 receives 63 the gNB-CU configuration update from the gNB-CU 62, and, if this gNB-CU configuration is successfully updated at the gNB-DU 61, the gNB-DU 61 sends 64 an acknowledgement to the gNB-CU 62. Further information above the gNB-CU configuration update procedure, and indeed the information included in the gNB-CU configuration update message 63 received by the gNB-DU 61 from the gNB- CU, can be found in [3], In accordance with embodiments of the present technique, as described above with respect to Figure 5, the list of potential NES cells / beams that the DU is able to activated / deactivate may be configured by the CU to the DU, such that it is then for the DU to make a decision on which cells / beams to be deactivated and when. This is because, while it is appropriate from a speed, efficiency, and power-saving point of view for the DU to make switching decisions rather than the CU, the CU has a better overview of which cells could be deactivated according to, for example, cell characteristics (e.g. macro cell, small cell, mobile cell), or overall network energy performance. Alternatively, or in addition, the CU may configure DU to report NES related assistance information, either in order to assist the CU in preparing this list, or to provide it with a more up-to-date or accurate overview of the cells and beams controlled by the DU for other or more general purposes.

[0100] The overall procedure comprises firstly, as can be understood from the message flow diagram of Figure 5, that the CU configures the DU to report NES-related assistance information, and configures when (i.e. under what conditions) the reporting should be triggered. Next, the CU configures a cell list containing the cells that could be potentially put into the sleep / deactivate state, together with some evaluation conditions to be performed by the DU so as to enable it to decide when to switch what cells (or beams) into the sleep state. After the DU receives the configuration (including the list and the evaluation conditions), the DU will start to evaluate the conditions associated with the cell (or beam) and if the conditions are satisfied, the DU will put the cell (or beam) into the sleep / deactivate state. After this, the DU may transmit feedback to the CU comprising an indication of the cells that it has switched / is going to switch into sleep state (or into the on state) using any appropriate legacy signalling. This may then, for example, enable the CU to make handover decisions and issue handover commands for UEs connected to the network via that cell that has been / is going to be switched to the sleep state.

[0101] Those skilled in the art would appreciate that some of these steps may not need to be present in one procedure, which may instead comprise only the transmission of NES assistance information (which the CU may use to make switching on / off decisions itself in a legacy manner) or may comprise only the transmission of a list of potential cells / beams for the DU to activate (which the CU may determine and form without having received any NES-related assistance information from the DU).

[0102] The CU may configure the DU to send the NES-related assistance information through use of an explicit request message. In other words, the DU may be configured to receive, from the CU, an explicit indication that the DU is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met, wherein the DU may determine that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received explicit indication. The CU can re-use / extend the legacy RESOURCE STATUS REQUEST to include this explicit indication, and / or the DU can re-use / extend the legacy RESOURCE STATUS UPDATE message to transmit the NES-related assistance information to the CU. Alternatively, a new set of messages may be defined.

[0103] Here, the first preconfigured conditions may either also be indicated by the CU (in the same signalling message (e.g. RESOURCE STATUS REQUEST) as this explicit indication or separately), or may be preconfigured and known to the DU, such as fixed in the relevant standards specification, where this explicit request message serves as a trigger for the DU to start transmitting the NES-related assistance information whenever the first preconfigured conditions are met. Indeed, one such first preconfigured condition may itself be the reception by the DU of the explicit request message.

[0104] Alternatively, the DU may already be configured with the requirement to transmit NES-related assistance information to the CU, but may require an indication of the preconfigured conditions to do so, as the CU may be able to change these over time dependent on network requirements. In other words, the DU may be configured to receive, from the CU, an indication of the at least one first preconfigured condition. Here, the DU may determine that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received indication of the at least one first preconfigured condition.

[0105] The DU may alternatively be pre-configured with the conditions to trigger the DU reporting, and may also be pre-configured with the requirement to transmit NES-related assistance information to the CU (or may require this to be explicitly signalled as described above).

[0106] The NES related assistance information may include one or more of the energy efficiency of the cell (or beam), the current energy state of the cell (or beam), for example, high, low, or medium, mobility information of UEs in the cell (or using the beam), such as a percentage of such UEs in high / low mobility, or a resource utilisation of the cell / beam. Here, this resource utilisation could relate to the amount of radio resources utilised (e.g. the ratio of resources) by the cell / beam, the number of active UEs connected to the cell / using the beam, a software / hardware load, etc. In other words, the assistance information may comprise one or more of (in any combination) a current energy efficiency of the at least one NES cell and / or the at least one NES beam, a current energy state of the at least one NES cell and / or the at least one NES beam, mobility information associated with communications devices connected to the at least one NES cell and / or communicating via the at least one NES beam, and a resource utilisation of the at least one NES cell and / or the at least one NES beam.

[0107] As described above, in order to reduce the signalling overheads for this reporting, the CU may configure associated conditions to trigger the DU performing reporting of the NES-related assistance information. For example, such conditions may comprise a pre-defined threshold, where only when measurements performed at the DU are higher / lower than this threshold, the reporting will be triggered. Alternatively, or in addition, the DU may be configured to transmit NES-related assistance information if it has been a certain time since the NES-related assistance information was last transmitted, or if this assistance information has become out of date. Such NES-related assistance information may therefore in some cases be performed periodically. In other words, the at least one first preconfigured condition may comprise one or more (in any combination) of a measured energy efficiency or measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being above a first predefined threshold, a measured energy efficiency or measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being below a second predefined threshold (or between two thresholds, e.g. above the first predefined threshold and below the second predefined threshold), and an amount of time since the DU last transmitted assistance information associated with the at least one NES cell and / or the at least one NES beam to the CU being greater than a predefined amount of time.

[0108] The contents of the cell list signalling received by the DU from the CU may at least include the following information. Firstly, such signalling will always include the cell list itself, including identifiers of the cells (or beams) in the list, which may be in the form of NR Cell Global Identities (NR CGI). This is the same format as used in the legacy signalling in GNB-CU CONFIGURATION UPDATE as described above with respect to Figure 6. The cell list signalling may also include, as described above, the conditions associated with the cell / beam under which the DU may then decide to switch the cell / beam on or off. In other words, the DU may be configured to receive, from the CU, an indication of a list of one or more NES cells and / or one or more NES beams associated with the DU, and to receive, from the CU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state. Here, this indicated list may be based on the NES-related assistance information transmitted by the DU (and indeed received by the DU in response to having transmitted that assistance information). The list of NES cells / beams may be the same as those indicated in the NES-related assistance information, or may include some further cells / beams not included in the NES-related assistance information signalling, or indeed there may be some cells / beams for which NES- related assistance information was signalled by the DU which are not included on the list signalled by the CU.

[0109] It should be noted that such conditions may alternatively be pre-configured and already known to the DU, such as fixed in the relevant standards specification, and so the cell list signalling does not need to specify them. In any case, however the DU determines such conditions, such conditions may comprise one or more of (in any combination) an energy efficiency of the cell / beam, a resource utilisation of the cell / beam, or an indication of exclusive cells / beams on sleep within the list.

[0110] The cell level energy efficiency is a vital factor to decide whether a cell should be deactivated. Here, the CU can configure a threshold, where if the energy efficiency is lower than a threshold, the cell could be deactivated. In other words, the at least one second preconfigured condition may comprise an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0111] When the resource utilisation of a cell is below a certain threshold, the DU may want to deactivate that cell. Here, this resource utilisation could relate to the amount of radio resources utilised (e.g. the ratio of resources) by the cell / beam, the number of active UEs connected to the cell / using the beam, a software / hardware load, etc. In other words, the at least one second preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0112] There are some cells which are mutually exclusive in respect of being in the sleep state at the same time, e.g. those cells with coverage to compensate for each other. If such cells exist in the list of cells that the DU is able to decide to switch on / off, then the CU should include such cell information (i.e. which cell(s) should not be deactivated at the same time) in the configuration, so that the DU is aware that if one cell is deactivated then it is not to deactivate the other. The same may be true of beams in addition (or alternatively) to cells. In other words, the at least one second preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

[0113] When DU finds that certain cells should not be configured as potentially candidate sleeping cells, for example because that cell is a particularly busy cell or is a cell with UEs that would suffer from that cell switching off, the DU may notify the CU of these cells to update the configuration. In other words, the DU may be configured to determine that one or more of the NES cells and / or NES beams on the indicated list should not have been included on the indicated list, and to transmit, to the CU, an indication of the one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list. This indication may simply include the IDs of those cells / beams that should not have been included on the indicated list, but may alternatively include a reason / cause for the removal of those cells / beams from the indicated list. Here, the CU may then update the list based on this (optionally after evaluating itself to confirm the DU is correct) and may later either transmit an updated list to the DU, or may wait until the next time it is to signal a list to the DU, where in such case the next signalled list would do so in accordance with the indication received from the DU in respect of the cells / beams that should not have been considered as candidates for the DU to switch off. Similarly, when the DU finds cells that should have been configured as potentially candidate sleeping cells, for example because the cell had been newly deployed or because the CU had made an error in not including it on the list, or because the list itself had been only partially or erroneously received by the DU, the DU may notify the CU of these cells to update the configuration. In other words, the DU may be configured to determine that one or more further NES cells and / or NES beams should have been included on the indicated list, and to transmit, to the CU, an indication of the one or more further NES cells and / or NES beams that should have been included on the indicated list. This indication may simply include the IDs of those cells / beams that should have been included on the indicated list, but may alternatively include a reason / cause for the inclusion of those cells / beams on the indicated list. Again, here, the CU may then update the list based on this (optionally after evaluating itself to confirm the DU is correct) and may later either transmit an updated list to the DU, or may wait until the next time it is to signal a list to the DU, where in such case the next signalled list would do so in accordance with the indication received from the DU in respect of the cells / beams that should have been considered as candidates for the DU to switch off.

[0114] In some arrangements of embodiments of the present technique, when the DU decides to activate / deactivate certain cells, it may notify the CU of its decision so that the CU can issue handover command to UEs. In other words, the DU may be configured to transmit, to the CU, an indication of the at least one of the NES cells and / or NES beams which the DU has switched / is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

[0115] The CU, as noted above, may then use this information (which cells / beams the DU has switched is going to switch on or off) to make decisions about handover of UEs, and to issue handover commands to such UEs. In other words, the CU may be configured to determine, for any of the at least one of the NES cells and / or NES beams that the DU has switched is going to switch from the on state to the energy saving state, whether one or more communications devices are connected to any of the at least one of the NES cells and / or are communicating via any of the at least one of the NES beams, and to transmit, to the one or more communications devices, a handover command to hand over to a new cell and / or beam. The new cell and / or beam may be an NES cell / beam or a non-NES cell / beam.

[0116] In some cases, the CU may send the potential switch-off cell list to UEs (in addition to the DU) as a conditional handover configuration, and when the DU decides which cell to switch off, the DU is able to send L2 / L1 signalling to the UE to trigger the handover execution. In other words, the CU may be configured to determine, for each of the NES cells and / or NES beams on the indicated list, that whether one or more communications devices are connected to that NES cell and / or are communicating via that NES beam, to transmit, to the one or more communications devices, an indication of the list of the NES cells and / or NES beams, and to transmit, to the one or more communications devices, a conditional handover command to hand over to a new cell and / or beam (where the new cell and / or beam may be an NES cell / beam or a non-NES cell / beam), the conditional handover being conditional on the DU transmitting, to each of the one or more communications devices, an indication that it has switched / is going to switch the NES cell to which that communications device is connected and / or the NES beam via which that communications device is communicating from the on state to the energy saving state. This indication may be a LI or L2 indication.

[0117] The introduction of a beam list from CU to DU in the message gNB-CU configuration update (as shown in Figure 6 and described above) is currently being discussed, to tell the DU which beam(s) should be switched off when the DU receives this gNB-CU configuration update message. Arrangements of embodiments of the present technique are therefore applicable to beams as well as cells; for example, the CU will configure the DU with a list of candidate beams (instead of or in addition to cells) to switch off, together with the conditions to apply in determining when and which beams to switch off, and it is then up to the DU to make switching on / off decisions in respect of such beams.

[0118] As described above, some arrangements of embodiments of the present technique propose the transmission by a DU of NES assistance information in accordance with certain conditions. Figure 7 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with such arrangements embodiments of the present technique. The process shown by Figure 7 is specifically a method of operating a DU of a wireless communications network.

[0119] The method begins in step Si l. The method comprises, in step S 12, determining that the DU is to transmit assistance information to a CU of the wireless communications network upon at least one preconfigured condition being met, wherein the assistance information is associated with at least one NES cell and / or at least one NES beam associated with the DU. In step S 13, the process comprises determining that the at least one preconfigured condition has been met. Then, in step S 14, the method comprises transmitting, to the CU upon determining that the at least one preconfigured condition has been met, the assistance information. The process ends in step S15.

[0120] As described above, some arrangements of embodiments of the present technique propose the reception by a DU of a list of NES cells / beams which it may switch on or off in accordance with certain conditions. Figure 8 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with such arrangements embodiments of the present technique. The process shown by Figure 8 is specifically a method of operating a DU of a wireless communications network.

[0121] The method begins in step S21. The method comprises, in step S22, receiving, from a CU of the wireless communications network, an indication of a list of one or more NES cells and / or one or more NES beams associated with the DU. In step S23, the process comprises receiving, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state. The process ends in step S24.

[0122] As described above, some arrangements of embodiments of the present technique propose the transmission by a DU of NES assistance information in accordance with certain conditions, and in response to the transmission of NES assistance information, the reception by a DU of a list of NES cells / beams which it may switch on or off in accordance with certain other conditions. Figure 9 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with such arrangements embodiments of the present technique. The process shown by Figure 9 is specifically a method of operating a DU of a wireless communications network.

[0123] The method begins in step S31. The method comprises, in step S32, determining that the DU is to transmit assistance information to a CU of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one NES cell and / or at least one NES beam associated with the DU. In step S33, the process comprises determining that the at least one first preconfigured condition has been met. Then, in step S34, the method comprises transmitting, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information. Following this, in step S35, the method comprises receiving, from the CU, an indication of a list of one or more NES cells and / or one or more NES beams associated with the DU. In step S36, the process next comprises receiving, from the CU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state. The process ends in step S37. Those skilled in the art would appreciate that the methods shown by Figures 7, 8, and 9 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such methods, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications system shown in Figure 5, it would be clear to those skilled in the art that they could be equally applied to other systems and procedures to those described herein.

[0124] Those skilled in the art would further appreciate that such infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure.

[0125] The following numbered paragraphs provide further example aspects and features of the present technique:

[0126] Paragraph 1. A method of operating a distributed unit, DU, of a wireless communications network, the method comprising determining that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, determining that the at least one first preconfigured condition has been met, and transmitting, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

[0127] Paragraph 2. A method according to Paragraph 1, comprising receiving, from the CU, an explicit indication that the DU is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met, wherein the DU determines that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received explicit indication.

[0128] Paragraph 3. A method according to Paragraph 1 or Paragraph 2, comprising receiving, from the CU, an indication of the at least one first preconfigured condition.

[0129] Paragraph 4. A method according to Paragraph 3, wherein the DU determines that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received indication of the at least one first preconfigured condition.

[0130] Paragraph 5. A method according to any of Paragraphs 1 to 4, wherein the assistance information comprises a current energy efficiency of the at least one NES cell and / or the at least one NES beam. Paragraph 6. A method according to any of Paragraphs 1 to 5, wherein the assistance information comprises a current energy state of the at least one NES cell and / or the at least one NES beam.

[0131] Paragraph 7. A method according to any of Paragraphs 1 to 6, wherein the assistance information comprises mobility information associated with communications devices connected to the at least one NES cell and / or communicating via the at least one NES beam.

[0132] Paragraph 8. A method according to any of Paragraphs 1 to 7, wherein the assistance information comprises a resource utilisation of the at least one NES cell and / or the at least one NES beam.

[0133] Paragraph 9. A method according to any of Paragraphs 1 to 8, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being above a first predefined threshold.

[0134] Paragraph 10. A method according to any of Paragraphs 1 to 9, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being below a second predefined threshold. Paragraph 11. A method according to any of Paragraphs 1 to 10, wherein the at least one first preconfigured condition comprises an amount of time since the DU last transmitted assistance information associated with the at least one NES cell and / or the at least one NES beam to the CU being greater than a predefined amount of time.

[0135] Paragraph 12. A method according to any of Paragraphs 1 to 11, comprising receiving, from the CU, an indication of a list of one or more NES cells and / or one or more NES beams associated with the DU, and receiving, from the CU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0136] Paragraph 13. A method according to Paragraph 12, wherein the indicated list is based on the assistance information transmitted by the DU. Paragraph 14. A method according to Paragraph 12 or Paragraph 13, wherein the at least one second preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0137] Paragraph 15. A method according to any of Paragraphs 12 to 14, wherein the at least one second preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0138] Paragraph 16. A method according to any of Paragraphs 12 to 15, wherein the at least one second preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

[0139] Paragraph 17. A method according to any of Paragraphs 12 to 16, comprising determining that the at least one second preconfigured condition has been met for at least one of the NES cells and / or NES beams on the indicated list, and switching, upon determining that the at least one second preconfigured condition has been met for the at least one of the NES cells and / or NES beams, the at least one of the NES cells and / or NES beams from the on state to the energy saving state or from the energy saving state to the on state.

[0140] Paragraph 18. A method according to Paragraph 17, comprising transmitting, to the CU, an indication of the at least one of the NES cells and / or NES beams which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

[0141] Paragraph 19. A method according to any of Paragraphs 12 to 18, comprising determining that one or more of the NES cells and / or NES beams on the indicated list should not have been included on the indicated list, and transmitting, to the CU, an indication of the one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

[0142] Paragraph 20. A method according to any of Paragraphs 12 to 19, comprising determining that one or more further NES cells and / or NES beams should have been included on the indicated list, and transmitting, to the CU, an indication of the one or more further NES cells and / or NES beams that should have been included on the indicated list.

[0143] Paragraph 21. A distributed unit, DU, of a wireless communications network, the DU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to determine that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, to determine that the at least one first preconfigured condition has been met, and to transmit, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

[0144] Paragraph 22. Circuitry for a distributed unit, DU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to determine that the circuitry is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, to determine that the at least one first preconfigured condition has been met, and to transmit, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

[0145] Paragraph 23. A method of operating a central unit, CU, of a wireless communications network, the method comprising receiving, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

[0146] Paragraph 24. A method according to Paragraph 23, comprising transmitting, to the DU, an explicit indication that the DU is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met.

[0147] Paragraph 25. A method according to Paragraph 23 or Paragraph 24, comprising transmitting, to the DU, an indication of the at least one first preconfigured condition.

[0148] Paragraph 26. A method according to any of Paragraphs 23 to 25, wherein the assistance information comprises a current energy efficiency of the at least one NES cell and / or the at least one NES beam. Paragraph 27. A method according to any of Paragraphs 23 to 26, wherein the assistance information comprises a current energy state of the at least one NES cell and / or the at least one NES beam.

[0149] Paragraph 28. A method according to any of Paragraphs 23 to 27, wherein the assistance information comprises mobility information associated with communications devices connected to the at least one NES cell and / or communicating via the at least one NES beam.

[0150] Paragraph 29. A method according to any of Paragraphs 23 to 28, wherein the assistance information comprises a resource utilisation of the at least one NES cell and / or the at least one NES beam.

[0151] Paragraph 30. A method according to any of Paragraphs 23 to 29, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being above a first predefined threshold.

[0152] Paragraph 31. A method according to any of Paragraphs 23 to 30, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being below a second predefined threshold. Paragraph 32. A method according to any of Paragraphs 23 to 31, wherein the at least one first preconfigured condition comprises an amount of time since the DU last transmitted assistance information associated with the at least one NES cell and / or the at least one NES beam to the CU being greater than a predefined amount of time.

[0153] Paragraph 33. A method according to any of Paragraphs 23 to 32, comprising determining, based on the assistance information received from the DU, one or more NES cells and / or one or more NES beams associated with the DU, transmitting, to the DU, an indication of a list of the determined one or more NES cells and / or the one or more NES beams associated with the DU and transmitting, to the DU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0154] Paragraph 34. A method according to Paragraph 33, wherein the at least one second preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0155] Paragraph 35. A method according to Paragraph 33 or Paragraph 34, wherein the at least one second preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0156] Paragraph 36. A method according to any of Paragraphs 33 to 35, wherein the at least one second preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

[0157] Paragraph 37. A method according to any of Paragraphs 33 to 36, comprising receiving, from the DU, an indication of at least one of the NES cells and / or NES beams on the indicated list which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

[0158] Paragraph 38. A method according to Paragraph 37, comprising determining, for any of the at least one of the NES cells and / or NES beams that the DU either has switched or is going to switch from the on state to the energy saving state, whether one or more communications devices are connected to any of the at least one of the NES cells and / or are communicating via any of the at least one of the NES beams, and transmitting, to the one or more communications devices, a handover command to hand over to a new cell and / or beam.

[0159] Paragraph 39. A method according to Paragraph 37 or Paragraph 38, comprising determining, for each of the NES cells and / or NES beams on the indicated list, that whether one or more communications devices are connected to that NES cell and / or are communicating via that NES beam, transmitting, to the one or more communications devices, an indication of the list of the NES cells and / or NES beams, and transmitting, to the one or more communications devices, a conditional handover command to hand over to a new cell and / or beam, the conditional handover being conditional on the DU transmitting, to each of the one or more communications devices, an indication that it either has switched or is going to switch the NES cell to which that communications device is connected and / or the NES beam via which that communications device is communicating from the on state to the energy saving state.

[0160] Paragraph 40. A method according to any of Paragraphs 33 to 39, comprising receiving, from the DU, an indication of one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

[0161] Paragraph 41. A method according to any of Paragraphs 33 to 40, comprising receiving, from the DU, an indication of one or more further NES cells and / or NES beams that should have been included on the indicated list.

[0162] Paragraph 42. A central unit, CU, of a wireless communications network, the CU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

[0163] Paragraph 43. Circuitry for a central unit, CU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

[0164] Paragraph 44. A method of operating a distributed unit, DU, of a wireless communications network, the method comprising receiving, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and receiving, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0165] Paragraph 45. A method according to Paragraph 44, wherein the indicated list is based on assistance information transmitted by the DU, the assistance information being associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU.

[0166] Paragraph 46. A method according to Paragraph 44 or Paragraph 45, wherein the at least one preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0167] Paragraph 47. A method according to any of Paragraphs 44 to 46, wherein the at least one preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0168] Paragraph 48. A method according to any of Paragraphs 44 to 47, wherein the at least one preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

[0169] Paragraph 49. A method according to any of Paragraphs 44 to 48, comprising determining that the at least one preconfigured condition has been met for at least one of the NES cells and / or NES beams on the indicated list, and switching, upon determining that the at least one preconfigured condition has been met for the at least one of the NES cells and / or NES beams, the at least one of the NES cells and / or NES beams from the on state to the energy saving state or from the energy saving state to the on state.

[0170] Paragraph 50. A method according to Paragraph 49, comprising transmitting, to the CU, an indication of the at least one of the NES cells and / or NES beams which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

[0171] Paragraph 51. A method according to any of Paragraphs 44 to 50, comprising determining that one or more of the NES cells and / or NES beams on the indicated list should not have been included on the indicated list, and transmitting, to the CU, an indication of the one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

[0172] Paragraph 52. A method according to any of Paragraphs 44 to 51, comprising determining that one or more further NES cells and / or NES beams should have been included on the indicated list, and transmitting, to the CU, an indication of the one or more further NES cells and / or NES beams that should have been included on the indicated list.

[0173] Paragraph 53. A distributed unit, DU, of a wireless communications network, the DU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to receive, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state. Paragraph 54. Circuitry for a distributed unit, DU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to receive, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0174] Paragraph 55. A method of operating a central unit, CU, of a wireless communications network, the method comprising transmitting, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and transmitting to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0175] Paragraph 56. A method according to Paragraph 55, wherein the indicated list is determined by the CU based on assistance information received from the DU, the assistance information being associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU. Paragraph 57. A method according to Paragraph 55 or Paragraph 56, wherein the at least one preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0176] Paragraph 58. A method according to any of Paragraphs 55 to 57, wherein the at least one preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

[0177] Paragraph 59. A method according to any of Paragraphs 55 to 58, wherein the at least one preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

[0178] Paragraph 60. A method according to any of Paragraphs 55 to 59, comprising receiving, from the DU, an indication of at least one of the NES cells and / or NES beams on the indicated list which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

[0179] Paragraph 61. A method according to Paragraph 60, comprising determining, for any of the at least one of the NES cells and / or NES beams that the DU either has switched or is going to switch from the on state to the energy saving state, whether one or more communications devices are connected to any of the at least one of the NES cells and / or are communicating via any of the at least one of the NES beams, and transmitting, to the one or more communications devices, a handover command to hand over to a new cell and / or beam.

[0180] Paragraph 62. A method according to Paragraph 60 or Paragraph 61, comprising determining, for each of the NES cells and / or NES beams on the indicated list, that whether one or more communications devices are connected to that NES cell and / or are communicating via that NES beam, transmitting, to the one or more communications devices, an indication of the list of the NES cells and / or NES beams, and transmitting, to the one or more communications devices, a conditional handover command to hand over to a new cell and / or beam, the conditional handover being conditional on the DU transmitting, to each of the one or more communications devices, an indication that it either has switched or is going to switch the NES cell to which that communications device is connected and / or the NES beam via which that communications device is communicating from the on state to the energy saving state.

[0181] Paragraph 63. A method according to any of Paragraphs 55 to 62, comprising receiving, from the DU, an indication of one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

[0182] Paragraph 64. A method according to any of Paragraphs 55 to 63, comprising receiving, from the DU, an indication of one or more further NES cells and / or NES beams that should have been included on the indicated list.

[0183] Paragraph 65. A central unit, CU, of a wireless communications network, the CU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to transmit to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0184] Paragraph 66. Circuitry for a central unit, CU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to transmit to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

[0185] Paragraph 67. A wireless communications system comprising a distributed unit, DU, according to Paragraph 21 or Paragraph 53, and a central unit, CU, according to Paragraph 42 or Paragraph 65. Paragraph 68. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Paragraphs 1 to 20, any of Paragraphs 23 to 41, any of Paragraphs 44 to 52, or any of Paragraphs 55 to 64.

[0186] Paragraph 69. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 68.

[0187] It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without detracting from the embodiments.

[0188] Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and / or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and / or processors.

[0189] Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

[0190] References

[0191] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0192] [2] TS 38.470, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl general aspects and principles (Release 17)”, 3GPP, V17.4.0, March 2023.

[0193] [3] TS 38.473, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl application protocol (F1AP) (Release 17)”, 3GPP, V17.4.1, April 2023.

[0194] [4] TS 38.401, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Architecture description (Release 17)”, 3GPP, V17.4.0, March 2023.

[0195] [5] TS 38 472, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl signalling transport (Release 15)”, 3GPP, V15.2.0, September 2018.

[0196] [6] TS 38.300, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 17)”, 3GPP, V17.4.0, March 2023.

[0197] [7] TS 23.501, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 18)”, 3GPP, V18.2.0, June 2023.

[0198] [8] RP -213554, “Study on network energy savings for NR,” (Huawei), 3GPP TSG RAN Meeting #94e, December 2021.

[0199] [8] TR 38.840, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Study on User Equipment (UE) power saving in NR (Release 16),” 3GPP, V16.0.0, June 2019.

[0200]

[0010] TR 38.864, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on network energy savings for NR (Release 18),” 3GPP, V18.1.0, March 2023.

[0201]

[0011] RP -220635, “Revised WID: Artificial Intelligence (AI) / Machine Learning (ML) for NG-RAN,” (CMCC, Ericsson), 3GPP TSG RAN Meeting #95e, March 2022.

[0202]

[0012] RP -231554, “Views on scope for NR Network Energy Savings in Rel-19,” (Qualcomm), 3GPP RAN Plenary #101, September 2023.

[0203]

[0013] RWS-230013, “Network Energy Saving Enhancements,” (Nokia, Nokia Shanghai Bell), 3GPP TSG RAN Rel-19 workshop, June 2023.

Claims

CLAIMSWhat is claimed is:

1. A method of operating a distributed unit, DU, of a wireless communications network, the method comprising determining that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, determining that the at least one first preconfigured condition has been met, and transmitting, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

2. A method according to Claim 1, comprising receiving, from the CU, an explicit indication that the DU is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met, wherein the DU determines that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received explicit indication.

3. A method according to Claim 1, comprising receiving, from the CU, an indication of the at least one first preconfigured condition.

4. A method according to Claim 3, wherein the DU determines that it is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met based on the received indication of the at least one first preconfigured condition.

5. A method according to Claim 1, wherein the assistance information comprises a current energy efficiency of the at least one NES cell and / or the at least one NES beam.

6. A method according to Claim 1, wherein the assistance information comprises a current energy state of the at least one NES cell and / or the at least one NES beam.

7. A method according to Claim 1, wherein the assistance information comprises mobility information associated with communications devices connected to the at least one NES cell and / or communicating via the at least one NES beam.

8. A method according to Claim 1, wherein the assistance information comprises a resource utilisation of the at least one NES cell and / or the at least one NES beam.

9. A method according to Claim 1, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being above a first predefined threshold.

10. A method according to Claim 1, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being below a second predefined threshold.

11. A method according to Claim 1, wherein the at least one first preconfigured condition comprises an amount of time since the DU last transmitted assistance information associated with the at least one NES cell and / or the at least one NES beam to the CU being greater than a predefined amount of time.

12. A method according to Claim 1, comprising receiving, from the CU, an indication of a list of one or more NES cells and / or one or more NES beams associated with the DU, and receiving, from the CU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

13. A method according to Claim 12, wherein the indicated list is based on the assistance information transmitted by the DU.

14. A method according to Claim 12, wherein the at least one second preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

15. A method according to Claim 12, wherein the at least one second preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

16. A method according to Claim 12, wherein the at least one second preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

17. A method according to Claim 12, comprising determining that the at least one second preconfigured condition has been met for at least one of the NES cells and / or NES beams on the indicated list, and switching, upon determining that the at least one second preconfigured condition has been met for the at least one of the NES cells and / or NES beams, the at least one of the NES cells and / or NES beams from the on state to the energy saving state or from the energy saving state to the on state.

18. A method according to Claim 17, comprising transmitting, to the CU, an indication of the at least one of the NES cells and / or NES beams which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

19. A method according to Claim 12, comprising determining that one or more of the NES cells and / or NES beams on the indicated list should not have been included on the indicated list, and transmitting, to the CU, an indication of the one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

20. A method according to Claim 12, comprising determining that one or more further NES cells and / or NES beams should have been included on the indicated list, andtransmitting, to the CU, an indication of the one or more further NES cells and / or NES beams that should have been included on the indicated list.

21. A distributed unit, DU, of a wireless communications network, the DU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to determine that the DU is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, to determine that the at least one first preconfigured condition has been met, and to transmit, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

22. Circuitry for a distributed unit, DU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to determine that the circuitry is to transmit assistance information to a central unit, CU, of the wireless communications network upon at least one first preconfigured condition being met, wherein the assistance information is associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, to determine that the at least one first preconfigured condition has been met, and to transmit, to the CU upon determining that the at least one first preconfigured condition has been met, the assistance information.

23. A method of operating a central unit, CU, of a wireless communications network, the method comprising receiving, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

24. A method according to Claim 23, comprising transmitting, to the DU, an explicit indication that the DU is to transmit the assistance information to the CU upon the at least one first preconfigured condition being met.

25. A method according to Claim 23, comprising transmitting, to the DU, an indication of the at least one first preconfigured condition.

26. A method according to Claim 23, wherein the assistance information comprises a current energy efficiency of the at least one NES cell and / or the at least one NES beam.

27. A method according to Claim 23, wherein the assistance information comprises a current energy state of the at least one NES cell and / or the at least one NES beam.

28. A method according to Claim 23, wherein the assistance information comprises mobility information associated with communications devices connected to the at least one NES cell and / or communicating via the at least one NES beam.

29. A method according to Claim 23, wherein the assistance information comprises a resource utilisation of the at least one NES cell and / or the at least one NES beam.

30. A method according to Claim 23, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being above a first predefined threshold.

31. A method according to Claim 23, wherein the at least one first preconfigured condition comprises a measured signal quality of signals received by the DU via the at least one NES cell and / or the at least one NES beam being below a second predefined threshold.

32. A method according to Claim 23, wherein the at least one first preconfigured condition comprises an amount of time since the DU last transmitted assistance information associated with the at least one NES cell and / or the at least one NES beam to the CU being greater than a predefined amount of time.

33. A method according to Claim 23, comprising determining, based on the assistance information received from the DU, one or more NES cells and / or one or more NES beams associated with the DU, transmitting, to the DU, an indication of a list of the determined one or more NES cells and / or the one or more NES beams associated with the DU and transmitting, to the DU, an indication of at least one second preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

34. A method according to Claim 33, wherein the at least one second preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

35. A method according to Claim 33, wherein the at least one second preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

36. A method according to Claim 33, wherein the at least one second preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

37. A method according to Claim 33, comprising receiving, from the DU, an indication of at least one of the NES cells and / or NES beams on the indicated list which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

38. A method according to Claim 37, comprising determining, for any of the at least one of the NES cells and / or NES beams that the DU either has switched or is going to switch from the on state to the energy saving state, whether one or morecommunications devices are connected to any of the at least one of the NES cells and / or are communicating via any of the at least one of the NES beams, and transmitting, to the one or more communications devices, a handover command to hand over to a new cell and / or beam.

39. A method according to Claim 37, comprising determining, for each of the NES cells and / or NES beams on the indicated list, that whether one or more communications devices are connected to that NES cell and / or are communicating via that NES beam, transmitting, to the one or more communications devices, an indication of the list of the NES cells and / or NES beams, and transmitting, to the one or more communications devices, a conditional handover command to hand over to a new cell and / or beam, the conditional handover being conditional on the DU transmitting, to each of the one or more communications devices, an indication that it either has switched or is going to switch the NES cell to which that communications device is connected and / or the NES beam via which that communications device is communicating from the on state to the energy saving state.

40. A method according to Claim 33, comprising receiving, from the DU, an indication of one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

41. A method according to Claim 33, comprising receiving, from the DU, an indication of one or more further NES cells and / or NES beams that should have been included on the indicated list.

42. A central unit, CU, of a wireless communications network, the CU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

43. Circuitry for a central unit, CU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a distributed unit, DU, of the wireless communications network, assistance information associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU, wherein the assistance information is received upon at least one first preconfigured condition being met.

44. A method of operating a distributed unit, DU, of a wireless communications network, the method comprising receiving, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, andreceiving, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

45. A method according to Claim 44, wherein the indicated list is based on assistance information transmitted by the DU, the assistance information being associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU.

46. A method according to Claim 44, wherein the at least one preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

47. A method according to Claim 44, wherein the at least one preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

48. A method according to Claim 44, wherein the at least one preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

49. A method according to Claim 44, comprising determining that the at least one preconfigured condition has been met for at least one of the NES cells and / or NES beams on the indicated list, and switching, upon determining that the at least one preconfigured condition has been met for the at least one of the NES cells and / or NES beams, the at least one of the NES cells and / or NES beams from the on state to the energy saving state or from the energy saving state to the on state.

50. A method according to Claim 49, comprising transmitting, to the CU, an indication of the at least one of the NES cells and / or NES beams which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

51. A method according to Claim 44, comprising determining that one or more of the NES cells and / or NES beams on the indicated list should not have been included on the indicated list, and transmitting, to the CU, an indication of the one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

52. A method according to Claim 44, comprising determining that one or more further NES cells and / or NES beams should have been included on the indicated list, and transmitting, to the CU, an indication of the one or more further NES cells and / or NES beams that should have been included on the indicated list.

53. A distributed unit, DU, of a wireless communications network, the DU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitryto receive, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to receive, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

54. Circuitry for a distributed unit, DU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive, from a central unit, CU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to receive, from the CU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

55. A method of operating a central unit, CU, of a wireless communications network, the method comprising transmitting, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and transmitting to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

56. A method according to Claim 55, wherein the indicated list is determined by the CU based on assistance information received from the DU, the assistance information being associated with at least one network energy saving, NES, cell and / or at least one NES beam associated with the DU.

57. A method according to Claim 55, wherein the at least one preconfigured condition comprises an energy efficiency of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

58. A method according to Claim 55, wherein the at least one preconfigured condition comprises a resource utilisation of the NES cells and / or NES beams on the indicated list being below a predefined threshold.

59. A method according to Claim 55, wherein the at least one preconfigured condition comprises whether the indicated list comprises one or more pairs of NES cells and / or one or more pairs of NES beams, wherein only one NES cell or NES beam of each of the pairs is able be in the energy saving state at any given time.

60. A method according to Claim 55, comprising receiving, from the DU, an indication of at least one of the NES cells and / or NES beams on the indicated list which the DU either has switched or is going to switch from the on state to the energy saving state or from the energy saving state to the on state.

61. A method according to Claim 60, comprising determining, for any of the at least one of the NES cells and / or NES beams that the DU either has switched or is going to switch from the on state to the energy saving state, whether one or more communications devices are connected to any of the at least one of the NES cells and / or are communicating via any of the at least one of the NES beams, and transmitting, to the one or more communications devices, a handover command to hand over to a new cell and / or beam.

62. A method according to Claim 60, comprising determining, for each of the NES cells and / or NES beams on the indicated list, that whether one or more communications devices are connected to that NES cell and / or are communicating via that NES beam, transmitting, to the one or more communications devices, an indication of the list of the NES cells and / or NES beams, and transmitting, to the one or more communications devices, a conditional handover command to hand over to a new cell and / or beam, the conditional handover being conditional on the DU transmitting, to each of the one or more communications devices, an indication that it either has switched or is going to switch the NES cell to which that communications device is connected and / or the NES beam via which that communications device is communicating from the on state to the energy saving state.

63. A method according to Claim 55, comprising receiving, from the DU, an indication of one or more of the NES cells and / or NES beams on the indicated list that should not have been included on the indicated list.

64. A method according to Claim 55, comprising receiving, from the DU, an indication of one or more further NES cells and / or NES beams that should have been included on the indicated list.

65. A central unit, CU, of a wireless communications network, the CU comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to transmit to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

66. Circuitry for a central unit, CU, of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a distributed unit, DU, of the wireless communications network, an indication of a list of one or more network energy saving, NES, cells and / or one or more NES beams associated with the DU, and to transmit to the DU, an indication of at least one preconfigured condition in accordance with which the DU is configured to switch the NES cells and / or NES beams on the indicated list from an on state to an energy saving state or from the energy saving state to the on state.

67. A wireless communications system comprising a distributed unit, DU, according to Claim 21 or Claim 53, and a central unit, CU, according to Claim 42 or Claim 65.

68. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1, Claim 23, Claim 44, or Claim 55.

69. A non-transitory computer-readable storage medium storing a computer program according to Claim 68.

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