Sending on-demand SIB1

Abstract

A method of operating a communications device is provided. The method comprises receiving, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication. The capability indication indicates whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network. The on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell. The method comprises transmitting a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted. The request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell. Alternatively, the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

Description

[0001] METHODS, COMMUNICATIONS DEVICES, AND INFRASTRUCTURE EQUIPMENT

[0002] BACKGROUND Field of Disclosure

[0003] The present disclosure relates to communications devices and infrastructure equipment of wireless communications networks and methods of operating such communications devices and infrastructure equipment.

[0004] The present application claims Paris Convention priority from European patent application number 24193107.0, filed on 6 August 2024, the contents of which are hereby incorporated by reference in their entirety.

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

[0013] 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.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

[0016] 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;

[0017] 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;

[0018] 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;

[0019] Figure 4 is a message flow diagram showing a typical four-step random access (RACH) procedure;

[0020] Figure 5 is a message flow diagram showing a typical two-step RACH procedure;

[0021] Figure 6 schematically illustrates the components of an SSB;

[0022] Figure 7 schematically illustrates an SSB burst set transmitted on SSB beams;

[0023] Figure 8 schematically illustrates a wireless communications network in which a communications device receives a WUS configuration from an assistance cell in accordance with use case 2 and use case 3;

[0024] Figure 9 schematically illustrates a wireless communications network in which a communications device requests and receives an on-demand SIB1 in accordance with use case 2;

[0025] Figure 10 schematically illustrates a wireless communications network in which a communications device requests and receives an on-demand SIB1 in accordance with use case 3;

[0026] Figure 11 is a flow diagram illustrating a method of operating a communications device in accordance with example embodiments; and

[0027] Figure 12 is a flow diagram illustrating a method of operating a communications device in accordance with example embodiments.

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

[0036] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 (which may 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures. Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 [3] and [4], 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.

[0045] 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 Eink 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.

[0046] 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, [5]). 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.

[0047] Random Access (RACH) Procedures

[0048] In wireless communications networks, such as LTE and NR type networks, a random access procedure may be used by communications devices to perform initial access with the wireless communications network. The random access procedure involves the communications device transmitting a preamble on a physical random access channel (PRACH), and so the procedure is commonly referred to as a RACH or PRACH procedure / process. The RACH procedure may be a two-step RACH procedure or a four-step RACH procedure as described in more detail below.

[0049] In addition, there exists Radio Resource Control (RRC) modes for communications devices. For example, it is common to support an RRC idle mode (RRC IDLE) and an RRC connected mode (RRC CONNECTED). A communications device in the RRC IDLE mode may transition to RRC CONNECTED mode, for example because it needs to transmit uplink data or respond to a paging request, by undertaking a random access procedure.

[0050] In addition to a communications device deciding itself to initiate a random access procedure to connect to the wireless communications network, it is also possible for the wireless communications network, e.g. a base station, to instruct a communications device in an RRC CONNECTED mode to initiate a random access procedure by transmitting to the communications device an instruction to do so. Such an instruction is sometimes referred to as a PDCCH order (Physical Downlink Control Channel order). There are various scenarios in which a network-triggered RACH procedure (PDCCH order) may arise. Figure 4 shows atypical four-step RACH procedure used in LTE systems such as that described by reference to Figure 1 which could also be applied to an NR wireless communications system such as that described by reference to Figure 2. A communications device (or UE), which may be in an RRC IDLE mode for example, may have some data which it needs to send to the network. To do so, the UE sends a random access preamble 51 (message 1) to a gNB. When the gNB detects the random access preamble 51, the gNB determines a random access preamble index / identity (RAPID) of the random access preamble 51. Assuming the random access preamble 51 is successfully received by the gNB, the gNB will transmit a random access response 52 message (message 2) to the communications device(s). The random access response 52 message may include the determined RAPID to indicate that the random access response 52 message is for the communications device(s) which transmitted the random access preamble 51 with that RAPID. The random access response 52 message carries a timing advance value such that the communications device can change its UL timing to compensate for the round trip delay caused by its distance from the gNB and grant uplink resources for the communications device to transmit the data in.

[0051] Following the reception of the random access response message 52, the communications device transmits the scheduled transmission of data 53 to the gNB (message 3), using the identity assigned to it in the random access response message 52. Assuming there are no collisions with other UEs, which may occur if another UE and the communications device send the same random access preamble 51 to the gNB at the same time and using the same frequency resources, the scheduled transmission of data 53 is successfully received by the gNB. The gNB will respond to the scheduled transmission 53 with a contention resolution message 54 (message 4).

[0052] In 5G / NR systems, an “inactive” RRC mode (RRC INACTIVE) may be used, where a UE is able to start data transfer with a low delay in the RRC INACTIVE mode without transition to the RRC CONNECTED mode. Various possible solutions have been proposed to permit this, one of which is a two-step RACH procedure. As will be appreciated, compared with the four-step RACH process, the two-step RACH process can provide a facility for transmitting data more quickly. Accordingly, it has been proposed to develop general MAC procedures covering both physical layer and higher layer aspects for the two-step RACH process. In general, the benefit of the two-step RACH procedure compared with the four-step RACH procedure is to reduce the time it takes for connection setup / resume procedure. For example, in an ideal situation, the two-step RACH will reduce the latency by halving the number of steps from four to two for initial access UEs. In addition, it is considered that a two-step RACH procedure has potential benefits for channel access in NR unlicensed spectrum (NR-U).

[0053] Broadly, the two-step RACH allows the combination of the transmission of the random access preamble 51 with the transmission of data 53 of Figure 4 as an initial transmission (“Message A” or “MsgA”), and similarly the combination of the transmission of the random access response 52 and contention resolution message 54 as a response (“Message B”, or “MsgB”). A fallback procedure may be provided to allow a RACH procedure which is started according to the specifications for a two-step RACH to instead proceed according to the four-step RACH procedure. Two-step RACH may be performed by communications devices in the RRC IDLE, RRC INACTIVE or RRC CONNECTED modes.

[0054] A message flow diagram illustrating the two-step RACH process is shown in Figure 5. As its name suggests, in the two-step RACH process, there are only two-steps as noted above. In the first step, the UE transmits a Message A 55 which comprises a RACH preamble 56 and data 57. The data 57 is transmitted on a shared uplink channel, such as a physical uplink shared channel, PUSCH that in a four-step RACH procedure would be transmitted in Message 3. More specifically, the choice of a particular preamble 56 may pre-configure the communications device to transmit the data 57 in pre-configured resources of the uplink shared channel. In the second step, the base station, having successfully received the Message A 55, responds with a Message B 58 which incorporates both a RAR, as would be carried by message 2 of the four-step RACH procedure described above, and the corresponding contention resolution and / or data (PDSCH) that in a four-step RACH procedure would be transmitted in Message 4.

[0055] Synchronisation Signal Block (SSB)

[0056] As will be known to one skilled in the art, the Synchronisation Signal Block (SSB) (also called as SS / PBCH block) is used for initial access and cell reselection. An example of an SSB is schematically illustrated in Figure 6.

[0057] As shown in Figure 6, the SSB comprises of a Primary Synchronisation Signal (PSS), a Secondary Synchronisation Signal (SSS) and a Physical Broadcast Channel (PBCH). The SSB comprises information for a communications device, such as a UE, to detect, measure and access a cell. The SSB shown in Figure 6 comprises 4 OFDM symbols and 240 subcarriers. The PSS and SSS each occupy 127 subcarriers. The PBCH occupies two OFDM symbols of 240 subcarriers and also 2 blocks of 48 subcarriers at the top and bottom of the SSS. The SSB may be configured with a periodicity, PSSB, of between 5 ms and 160 ms. For initial cell selection, the UE assumes a periodicity of 20ms.

[0058] An SSB burst set comprises a set of one or more time-multiplexed SSBs. Each SSB transmitted in a burst set uses a different downlink beam, thereby enabling beam sweeping to be implemented for SSBs. An SSB burst set may be confined within 5 ms and may comprise up to 4, 8 and 64 SSBs for frequency bands below 3 GHz, between 3 GHz - 6 GHz and for FR2 respectively. As will be understood by one skilled in the art, SSB burst sets may be transmitted periodically.

[0059] An example SSB burst set in the case of 3 GHz - 6 GHz frequency is shown in Figure 7. The SSB burst set shown in Figure 7 comprises 8 SSBs labelled as SSB#1, SSB#2, SSB#3, SSB#4, SSB#5, SSB#6, SSB#7 and SSB#8 respectively. Each of the SSBs in the burst set is transmitted using a different downlink beam. In this example, 2 SSBs are configured per slot within 4 slots. Furthermore, the burst set is transmitted with a periodicity, PSSB, of 20 ms. Although not shown in Figure 7, the SSB burst set is transmitted by infrastructure equipment of a wireless communications network (such as a gNB) and received by a communications device (such as a UE).

[0060] The UE measures a signal quality of each SSB in the SSB burst set. The UE may then select one of the downlink beams based on the measured signal quality. For example, the UE may select the downlink beam with the highest measured signal quality provided that the measured signal quality is above a threshold (such as RSRP threshold). Then, the UE determines an uplink beam corresponding to the downlink beam to use for synchronisation with the infrastructure equipment. As will be appreciated by one skilled in the art, corresponding uplink and downlink beams form beam pairs which overlap. Therefore, the measurements of the signal quality of a downlink beam are an indication of the signal quality of the corresponding uplink beam in the beam pair.

[0061] In one example, the measured signal quality of an SSB is an RSRP of the SSB. The UE may measure the RSRP of each SSB in the SSB burst set and select the downlink beam on which the SSB with the highest RSRP was transmitted provided this measured RSRP is above a threshold (such as rsrp-ThresholdSSB).

[0062] The measurement of the RSRP of an SSB may be referred to as “SS-RSRP”. The measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where SSS is transmitted. Alternatively, or in addition, the measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where PBCH DMRS is transmitted.

[0063] In other examples, the measured signal quality of an SSB may be a Reference Signal Received Quality (SS-RSRQ) of the SSB. The SS-RSRQ is defined as the ratio of N x SS-RSRP / RSSI (Received Signal Strength Indicator), where N is the number of resource blocks. For example, the RSSI in NR is measured in one or more OFDM symbols in a SS / PBCH Block Measurement Time Configuration (SMTC). The SMTC is a configuration to the UE that sets a time window for SSB measurements by using the UE. The OFDM symbols used for RSSI measurement can be configured by higher layers.

[0064] In initial access, after determining the uplink beam, the UE initiates a RACH procedure by transmitting PRACH on the determined uplink beam. For example, the UE may transmit message 51 or message 55 on the determined uplink beam. The PRACH may be transmitted on PRACH resources which have been configured for the UE to transmit the PRACH as part of initial access. For example, the PRACH may be transmitted in one of a plurality of RACH Occasions (ROs) configured for transmitting the PRACH.

[0065] Network Energy Saving (NES)

[0066] 3GPP is currently discussing network energy saving (NES). By reducing energy consumption in wireless communications networks, the impact of wireless communications on the environment can be reduced. For example, if less energy is consumed in wireless communications networks, fewer fossil fuels are burned, there are fewer greenhouse gas emissions and therefore environmental sustainability is improved. Furthermore, the reduction of energy consumption in wireless communications networks can reduce costs incurred by network operators.

[0067] 5G / NR can handle advanced services and applications requiring very high data rates (for example, XR). Additionally, 5G / NR networks are becoming denser, using more antennas, and utilising larger bandwidths and an increasing number of frequency bands. Therefore, in at least some cases, energy consumption in 5G / NR is increasing. Since 5G / NR is becoming increasingly pervasive across various industries and geographical areas, it is becoming increasingly important to reduce the environmental impact of 5G / NR networks. NES solutions are therefore required.

[0068] In addition, energy consumption has become a key part of the operating expenses (OPEX) for network operators. According to a report from the Global System for Mobile Communications Association (GSMA) [6], the energy cost of mobile networks accounts for approximately 23% of total operator costs. Most of the energy consumption comes from the radio access network and in particular from the Active Antenna Unit (AAU), with data centres and fibre transport accounting for a smaller share of the energy consumption. The energy consumption of a radio access network can be split into two parts: (1) a dynamic part which is only consumed when data transmission / reception is ongoing, and (2) a static part which is consumed all the time to maintain the necessary operation of the radio access network equipment, even when data transmission / reception is not on-going. Further details on NES can be found m [7],

[0069] In Release 19 of the 3GPP standards, an NES work item has been approved ([8]). The objectives of the work item are the following:

[0070] 1. Specify procedures and signaling method(s) to support on-demand SSB SCell operation for UEs in connected mode configured with CA, for both intra- / inter-band CA.

[0071] 2. Study procedures and signaling method(s) to support on-demand SIB1 for UEs in idle / inactive mode, including:

[0072] 3. Specify adaptation of common signal / channel transmissions. NES System Information (SI)

[0073] As will be understood by a person skilled in the art, system information is transmitted by infrastructure equipment of a wireless communications network to communications devices in a cell provided by the infrastructure equipment. The system information informs the communications devices on how to access services provided by the wireless communications network. The system information comprises a master information block (MIB), system information block type 1 (SIB1) and a plurality of other system information blocks (SIBs). The MIB is broadcasted in the PBCH in each SSB.

[0074] The MIB comprises information required to decode SIB1. For example, MIB comprises a cell barred bit, system frame number, and a PDCCH configuration for SIB1, for example. SIB1 comprises information required for accessing the cell (for example, random access parameters such as time / frequency resources for PRACH (e.g an RO configuration), preambles, or barring parameters). In initial access, the UE transmits a PRACH in an RO of the RO configuration indicated by SIB1, thereby initiating a random access procedure. After the random access procedure, the UE may enter the RRC_Connected mode. Therefore, MIB and SIB1, which are defined as the “minimum system information”, together provide all the information which is required for initial access. Accordingly, MIB is defined as the part of ‘minimum system information’ whilst SIB1 is defined as the “remaining minimum SI” (i.e. the other part of the minimum system information). SIB1 may comprise scheduling information of the other SIBs (for example, mapping of SIBs to SI messages, periodicity of other SIBs and Si-window size). SIB1 is periodically broadcasted over a downlink shared channel (DL-SCH), but may be provided on-demand as explained below. Periodically broadcasted SIB1 is typically an “always-on” signal. The information comprised in the other SIBs is not required for initial access and so SIB1 may comprise an indication of whether the other SIBs are provided on-demand, in which case, SIB 1 may also comprise an indication of a PRACH configuration for use by the UE to request the other SIBs. SIB 1 may also comprise radio resource configuration information common to all communications devices in the cell in which the SIB1 is transmitted. SIB1 may also comprise cell barring information.

[0075] The other SIBs may comprise one or more of: SIB2-SIB18 and SIBpos.

[0076] — SIB2 comprises cell re-selection information, mainly related to the serving cell;

[0077] — SIB3 comprises information about the serving frequency and intra-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);

[0078] — SIB4 comprises information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters), which can also be used for NR idle / inactive measurements;

[0079] — SIB5 comprises information about E-UTRA frequencies and E-UTRA neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);

[0080] — SIB6 comprises an ETWS primary notification;

[0081] — SIB7 comprises an ETWS secondary notification;

[0082] — SIB8 comprises a CMAS warning notification;

[0083] — SIB9 comprises information related to GPS time and Coordinated Universal Time (UTC);

[0084] — SIB 10 comprises the Human-Readable Network Names (HRNN) of the NPNs listed in SIB1;

[0085] — SIB11 comprises information related to idle / inactive measurements;

[0086] — SIB 15 comprises information related to disaster roaming; — SIB 16 comprises slice-based cell reselection information;

[0087] — SIB 17 comprises information related to TRS configuration for UEs in

[0088] RRC IDLE / RRC INACTIVE;

[0089] — SIBpos comprises positioning assistance data as defined in TS 37.355 and TS 38.331;

[0090] — SIB 18 comprises information related to the Group IDs for Network selection (GINs) associated with SNPNs listed in SIB1.

[0091] Further information regarding existing SI can be found in TS38.300 vl8.0.0, the contents of which are hereby incorporated by reference in their entirety.

[0092] As mentioned above, the approved NES work item in Release 19 of the 3GPP standards has an objective to specify adaptations of common signal / channel transmissions. For example, the adaptation of SIB1 transmissions is being considered for NES.

[0093] On-Demand SIB1

[0094] As one example of an adaptation, it has been suggested to introduce an on-demand SIB1. In other words, instead of infrastructure equipment of the wireless communications network periodically broadcasting SIB1, it has been proposed for infrastructure equipment (i.e. NES infrastructure equipment) to broadcast SIB1 only in response to a request (e.g. an uplink wake-up signal (WUS)) from a communications deice such as a UE. Since the SIB1 would thereby be transmitted less often, network energy savings would be increased.

[0095] In Release- 19 of the 3GPP standards, the following three use cases for on-demand SIB1 transmission have been defined:

[0096] Use Case 1: A UE receives an uplink WUS configuration from an NES cell; the UE transmits an uplink WUS to the NES cell using the uplink WUS configuration; and the UE receives an on-demand SIB1 from the NES cell.

[0097] Use Case 2: A UE receives an uplink WUS configuration from an assistance cell; the UE transmits an uplink WUS to the NES cell using the uplink WUS configuration; and the UE receives an on-demand SIB1 from the NES cell.

[0098] Use Case 3: A UE receives an uplink WUS configuration from an assistance cell; the UE transmits an uplink WUS to the assistance cell using the uplink WUS configuration; and the UE receives an on- demand SIB1 from the assistance cell.

[0099] 3GPP have agreed that use case 2 and use case 3 will be the subject of further study. Use case 2 and use case 3 are described in more detail below with respect to Figure 8, Figure 9 and Figure 10.

[0100] Figure 8 schematically illustrates a wireless communications network in which a communications device receives a WUS configuration from an assistance cell in accordance with use case 2 and use case 3. As shown in Figure 8, a core network 90 is connected to NES infrastructure equipment 92 and to assistance infrastructure equipment 96. The NES infrastructure equipment 92 provides an NES cell 94 and the assistance infrastructure equipment 96 provides an assistance cell 95. The assistance infrastructure equipment 96 is infrastructure equipment which assists the NES infrastructure equipment 92 to reduce its energy consumption as will become apparent from an understanding of the description of Figures 8, 9 and 10. The assistance infrastructure equipment 96 may be a TRP or gNB, for example. The NES infrastructure equipment 92 may be a TRP or gNB, for example. The assistance infrastructure equipment 96 and the NES infrastructure equipment 92 may each be a TRP belonging to the same gNB or to different gNBs. Although the coverage of the NES cell 94 and the assistance cell 95 are shown as not overlapping in Figures 8, 9 and 10, it should be noted that the NES cell 94 and the assistance cell coverages 95 may overlap partially or fully in some examples.

[0101] In Figure 8, a communications device 98 (such as a UE) receives, from the assistance infrastructure equipment 96, an uplink WUS configuration 100 for transmitting an uplink WUS. The uplink WUS configuration may comprise an indication of time and / or frequency resources for the communications device 98 to use to transmit the uplink WUS.

[0102] Figure 9 schematically illustrates a wireless communications network in which a communications device requests and receives an on-demand SIB1 in accordance with use case 2. Following reception of the uplink WUS configuration 100 as described with reference to Figure 8, the communications device 98 transmits an uplink WUS 110 to the NES infrastructure equipment 92 in accordance with the uplink WUS configuration 100. In response, the NES infrastructure equipment 92 transmits an on-demand SIB1 112 to the communications device 98. Therefore, the uplink WUS may alternatively be referred to as a request for the on-demand SIB1. The on-demand SIB1 122 is an on-demand SIB1 which is applicable to the NES cell 94 and comprises information required for accessing the NES cell 94. As will be appreciated, the assistance infrastructure equipment 96 assists the NES infrastructure equipment 92 to reduce energy consumption in use case 2 because the assistance infrastructure equipment 96 transmits the WUS configuration 100 on behalf of the NES infrastructure equipment 92. In the example of Figure 9, the communications device 98 may store the uplink WUS configuration 100 received from the assistance infrastructure equipment, move to the NES cell 94, and then transmit the uplink WUS 110 to the NES infrastructure equipment 92.

[0103] Figure 10 schematically illustrates a wireless communications network in which a communications device requests and receives an on-demand SIB1 in accordance with use case 3. Following reception of the uplink WUS configuration 100 as described with reference to Figure 8, the communications device 98 transmits an uplink WUS 120 to the assistance infrastructure equipment 96 in accordance with the uplink WUS configuration 100. In response, the assistance infrastructure equipment 96 transmits an on-demand SIB1 122 to the communications device 98. The on-demand SIB1 122 is an on-demand SIB1 which is applicable to the NES cell 94, and comprises information for accessing the NES cell 94. As will be appreciated, the assistance infrastructure equipment 96 assists the NES infrastructure equipment 92 to reduce energy consumption in use case 3 because the assistance infrastructure equipment 96 transmits the on-demand SIB1 122 on behalf of the NES infrastructure equipment 92 (and therefore the NES infrastructure equipment 92 does not need to transmit the on-demand SIB 1 122 applicable to the NES cell 94). The assistance infrastructure equipment 96 may obtain the on-demand SIB1 from the NES infrastructure equipment 92 via an Xn, or X2, interface, from the core network 90, or from a component implementing Operations, Administration and Maintenance (0AM), for example.

[0104] Cell Camping

[0105] As will be appreciated by a person skilled in the art, in initial cell selection, a communications device may scan all radio frequency channels on operating bands according to the capabilities of the communications device to find a suitable cell for camping on. On each frequency channel, the communications device is only required to search for the strongest cell (e.g. the cell with the best radio conditions such as the best RSRP). The communications device acquires the SIB1 applicable to the strongest cell on each frequency channel, and applies cell selection criteria to the strongest cell on each frequency channel. Based on the cell selection criteria, the communications device selects a cell to initially camp on. After camping on the cell, the communications device will monitor control channels of the cell. For example, the communications deice may receive system information from a Public Land Mobile Network (PLMN) receive a paging message a cell reselection procedure. As will be appreciated by a person skilled in the art, in cell reselection, the communications device may rank all cells that fulfil the cell selection criteria, based on system information applicable to the cell which the communications device is currently camped on (i.e. the serving cell). The communications device selects the highest ranking cell (e.g. the cell with the best radio conditions such as the best RSRP) which is better than the serving cell as a candidate for re-selection. However, before performing the cell reselection, the communications device performs a check on the candidate cell by acquiring the MIB and SIB1 applicable to the candidate cell to check if there is any access restriction. The communications device again checks whether the candidate cell fulfils the cell selection criteria by using the MIB and SIB1 applicable to the candidate cell.

[0106] Referring back to Figure 8, the communications device 98 is shown camped on the assistance cell 95. Accordingly, the communications device 98 can acquire and store system information applicable to the assistance cell 98.

[0107] After camping on the assistance cell 98, the communications device 98 may, according to use case 3 shown in Figure 10, transmit a request 120 to the assistance infrastructure equipment 96 for the on- demand SIB1 122 applicable to the NES infrastructure equipment 92. The communications device 98 can then use the on-demand SIB1 122 applicable to the NES infrastructure equipment 92 to determine whether to reselect the NES cell 94. If the NES cell 94 is reselected, the communications device 92 may transmit a RACH to the NES infrastructure equipment 92 in order to access in the NES cell 94.

[0108] After camping on the assistance cell 98, the communications device 98 may, according to use case 2 shown in Figure 9, transmit a request 110 to the NES infrastructure equipment 92 for the on-demand SIB1 112 applicable to the NES infrastructure equipment 92 if the NES infrastructure equipment 92 is chosen as a cell re-selection candidate. The communications device 98 can then use the on-demand SIB1 122 applicable to the NES infrastructure equipment 92 to determine whether to reselect the NES cell 94. If the NES cell 94 is reselected, the communications device 92 may transmit a RACH to the NES infrastructure equipment 92 in order to access in the NES cell 94.

[0109] Co-existence of Use Case 2 and Use Case 3

[0110] The present inventors have recognised that it is possible to support co-existence of use case 2 and use case 3 in wireless communications networks. For example, the assistance infrastructure equipment 96 may store a plurality of on-demand SIB Is of the first type each of which is applicable to a respective one of a plurality of NES cells. In this case, the assistance infrastructure equipment 96 may support use case 2 for one or more of the plurality of NES cells and may support use case 3 for one or more others of the plurality of NES cells. However, the present inventors have recognised that technical problems arise when implementing the co-existence of use case 2 and use case 3 in wireless communications networks. For example, referring to Figure 8, if the communications device 98 receives the WUS configuration 100 from the assistance infrastructure equipment 96, the communications device 98 does not know where to transmit the request for the on-demand SIB 1 applicable to the NES cell 94. In use case 2, the request should be transmitted to the NES infrastructure equipment 92 while in use case 3 the request should be transmitted to the assistance infrastructure equipment 96. Accordingly, the communications device 98 may transmit the request to the incorrect infrastructure equipment, therefore leading to signalling wastage.

[0111] There is therefore a need for communications device, infrastructure equipment and methods which can improve communications efficiency.

[0112] In view of the above, there is provided a method of operating a communications device as shown in Figure 11. The method starts in step S 1.

[0113] In step S2, the method comprises receiving, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication.

[0114] The capability indication indicates whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network. The on-demand SIB of the first type applicable to the NES cell comprises information required to access the NES cell.

[0115] For ease of reference, the on-demand SIB of the first type applicable to the NES cell may alternatively be referred to as “NES SIB1”. Although, in some embodiments, the NES SIB1 is specifically referring to “system information block type 1” as currently defined in 3GPP specifications (e.g. TS38.331 v. 18.2.0, the contents of which are hereby incorporated by reference in their entirety), example embodiments are not limited to the system information block type 1 currently defined in 3GPP specifications and are equally applicable to any future on-demand SIB of a particular type which comprises information required to access the NES cell.

[0116] In some embodiments the NES SIB1 may comprise, for the NES cell, one or more of: random access parameters such as time / frequency resources for PRACH (e.g an RO configuration); preambles; and barring parameters.

[0117] Similarly, for ease of reference, an SIB of the first type applicable to the assistance cell may alternatively be referred to as the “assistance SIB1” throughout this disclosure. Although, in some embodiments, the assistance SIB1 is specifically referring to “system information block type 1” as currently defined in 3GPP specifications, example embodiments are not limited to the system information block type 1 currently defined in 3GPP specifications and are equally applicable to any future SIB of a particular type which comprises information required to access the assistance cell.

[0118] In some embodiments the assistance SIB 1 may comprise, for the assistance cell, one or more of: random access parameters such as time / frequency resources for PRACH (e.g an RO configuration); preambles; and barring parameters.

[0119] The NES SIB1 is “applicable to the NES cell” in the sense that the NES SIB1 comprises information regarding the NES cell. The assistance SIB1 is “applicable to the assistance cell” in the sense that the assistance SIB1 comprises information regarding the assistance cell. As will be explained in more detail below, the assistance SIB 1 may also comprise information regarding the NES cell in accordance with example embodiments.

[0120] In step S3, the method comprises transmitting a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted.

[0121] The request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the SIB of the first type applicable to the NES cell. Alternatively, the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the SIB of the first type applicable to the NES cell. The method ends in step S4.

[0122] By receiving the capability indication from the assistance infrastructure equipment, the communications device can transmit the request for the NES SIB 1 to the correct infrastructure equipment (i.e. the assistance infrastructure equipment in use case 3 or the NES infrastructure equipment in use case 2). Therefore, a situation in which the communications device transmits the request to the incorrect infrastructure equipment can be avoided. Therefore, signalling wastage is avoided and communications efficiency is improved.

[0123] In some embodiments, the communications device receives, from the assistance infrastructure equipment, system information applicable to the assistance cell (alternatively referred to as “assistance system information”). In some embodiments, the capability indication may be comprised in the assistance system information. For example, the capability indication may be comprised in an assistance SIB1 of the assistance system information, the capability indication may be comprised in an assistance MIB of the assistance system information (alternatively referred to as an MIB applicable to the assistance cell), or the capability indication may be comprised in a new SIB type (e.g. SIB36) in the assistance system information. The assistance information may be, for example, on-demand assistance information.

[0124] In some embodiments, the assistance SIB comprises scheduling information indicating a schedule for transmitting one or more other types of SIB applicable to the assistance cell (alternatively referred to as one or more other types of assistance SIBs). The assistance SIBs may comprise any, or all, of SIB2- SIB18 and SIBpos. One of the assistance SIBs is an NES support SIB. The NES support SIB is an SIB which indicates that the assistance infrastructure equipment is configured to transmit, in the assistance cell, one or more on-demand SIB Is applicable to one or more respective NES cells (alternatively referred to as NES SIB Is) provided by one or more respective NES infrastructure equipment.

[0125] The NES support SIB may Indicate one or more of the following:

[0126] — a Cell Global Identity (CGI) of each of the one or more NES cells for which the assistance infrastructure equipment is configured to transmit an NES SIB 1 ;

[0127] — a physical cell identifier (PCI) of each of the one or more NES cells for which the assistance infrastructure equipment is configured to transmit an NES SIB 1 ;

[0128] — a frequency of each of the one or more NES cells for which the assistance infrastructure equipment is configured to transmit an NES SIB 1.

[0129] In some embodiments, the assistance system information may comprise the NES SIB 1.

[0130] Implicit Notification

[0131] In some embodiments, the capability indication is comprised in the scheduling information in the assistance SIB. For example, the capability indication implicitly indicates that the assistance infrastructure equipment is configured to transmit the NES SIB 1 by indicating the presence of the schedule for transmitting the NES support SIB in the scheduling information. In other words, the communications device assumes, based on a determination that the NES support SIB is scheduled for transmission, that the assistance infrastructure equipment is configured to transmit the NES SIB 1.

[0132] Accordingly, in some embodiments, the communications device may transmit the request to the assistance infrastructure equipment if the scheduling information indicates that the NES support SIB is present. The communications device may check the NES support SIB to determine which NES cells have NES SIB Is in the NES support SIB. Alternatively, the communications device may transmit the request to the NES infrastructure equipment if the scheduling information indicates that the NES support SIB is not present. Explicit Notification

[0133] In some embodiments, the capability indication is comprised in the NES support SIB. In such embodiments, the capability indication explicitly indicates that the assistance infrastructure equipment is configured to transmit the NES SIB 1. For example, the capability indication may comprise one or more of:

[0134] — a Cell Global Identity (CGI) of the NES cell,

[0135] — a physical cell identifier (PCI) of the NES cell, and

[0136] — a frequency of the NES cell.

[0137] Accordingly, in some embodiments, if the communications device determines that the CGI, PCI and / or frequency of the NES cell is among the CGI, PCI and / or frequency of the one or more NES cells indicated in the NES support SIB, the communications device transmits the request to the assistance infrastructure equipment. Otherwise, the communications device transmits the request to the NES infrastructure equipment.

[0138] Capability Indication in WUS Configuration

[0139] In some embodiments, the capability indication is comprised in a WUS configuration transmitted by the assistance infrastructure equipment. The WUS configuration may alternatively be referred to as a configuration of time and / or frequency resources for transmitting the request for the NES SIB 1.

[0140] By including the capability indication in assistance system information, or in a WUS configuration, the capability indication can be efficiently indicated because existing signals are re-used, or adapted, to provide the capability indication.

[0141] Up-to-Date SIB1

[0142] As will be explained in more detail below, the present inventors have recognised that technical problems can arise in the implementation of use case 3 and, in particular, technical problems arise in ensuring the communications device is in possession of an up-to-date on-demand SIB1 applicable to the NES cell (i.e. an NES SIB1).

[0143] As previously explained with reference to Figure 10, in use case 3, the assistance infrastructure equipment 96 transmits an on-demand SIB 1 applicable to the NES cell 94 on behalf of the NES infrastructure equipment 92. The assistance infrastructure equipment 96 may obtain the on-demand SIB1 from the NES infrastructure equipment 92 via an Xn, or X2, interface, from the core network 90, or from a component implementing 0AM, for example. However, the present inventors have recognised that there may be a delay in a change in content of the on-demand SIB 1 which may lead to the assistance infrastructure equipment 96 storing an out-of-date version of the on-demand SIB 1. For example, the NES infrastructure equipment 92 may update the on-demand SIB 1 and not notify the assistance infrastructure equipment 96 in a timely manner. Similarly, the 0AM or the core network 90 may store an out-of-date on-demand SIB 1 and therefore the assistance infrastructure equipment 96 receives the out-of-date on-demand SIB 1 from the 0AM or core network 90. This will lead to the out-of-date on-demand SIB1 being stored by the communications device 98 when the assistance infrastructure equipment 96 transmits the out-of-date on- demand SIB1 to the communications device 98. This may lead to the communications device 98 attempting and failing to access the NES cell 94 because it is using an out-of-date SIB1, thereby leading to signalling wastage. For example, the SIB1 may have been updated to change an access restriction rule. The access restriction rule may indicate that the communications device 98 is not permitted to access the NES cell 94. However, the communications device 98 does not know this because it does not have the updated SIB1. Therefore, the communications device 98 may attempt and fail to access the NES cell 94. In another example, the SIB1 may have been updated to change RACH resources for transmitting RACH. However, the communications device 98 does not know this because it does not have the updated SIB1. Therefore, the communications device may attempt to transmit RACH on out-of-date RACH resources indicated in the out-of-date SIB 1. Accordingly, the communications device may attempt and fail to access the NES cell 94.

[0144] This is a particularly challenging problem in inter-vendor scenarios where different vendors provide the assistance infrastructure equipment and the NES infrastructure equipment (and / or provide different OAMs for the assistance infrastructure equipment and the NES infrastructure equipment). In such scenarios, the assistance infrastructure equipment and the NES infrastructure equipment may not share system information with each other in real time. Alternatively, or additionally, the assistance infrastructure equipment may obtain its system information from an 0AM of one vendor and the NES infrastructure equipment may obtain its system information from the 0AM of another vendor; and the OAMs belonging to different vendors may not share system information with each other in real time. This means there may be a delay in the update of an NES SIB 1 being transmitted by assistance infrastructure equipment.

[0145] There is therefore a need for communications device, infrastructure equipment and methods which can improve communications efficiency.

[0146] In view of the above, there is provided a method of operating a communications device as shown in Figure 12. The method starts in step Si l.

[0147] In step S 12, the method comprises receiving a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell.

[0148] The NES cell is provided by NES infrastructure equipment of a wireless communications network for a communications device.

[0149] The on-demand SIB of the first type is transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device. The SIB of the first type applicable to the NES cell comprises information required to access the NES cell.

[0150] The validity indication may be received by the communications device from the NES infrastructure equipment or the assistance infrastructure equipment, for example.

[0151] In step SI 3, the method comprises determining, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

[0152] The method ends in step S14.

[0153] By receiving an indication of the validity of the NES SIB1, the communications device can determine whether or not to use the NES SIB1 for accessing the NES cell. If, for example, the communications device determines not to use the NES SIB1, the communications device may use an updated NES SIB1 for accessing the NES cell. The communications device may wait for the updated NES SIB 1 or may transmit a request to the assistance infrastructure equipment for the updated SIB 1. Therefore, the likelihood of the communications device attempting and failing to access the NES cell based on an out- of-date NES SIB1 is reduced. Consequently, signalling wastage can be avoided and therefore communications efficiency is improved.

[0154] System Information Update Timing Notification In some embodiments, the validity indication comprises an indication of an update schedule for NES SIB 1. For example, the NES infrastructure equipment may transmit an indication of the update schedule to the assistance infrastructure equipment (via an Xn, or X2, interface, for example). Then, the assistance infrastructure equipment transmits the indication of the update schedule for the NES SIB 1 in the assistance cell for the communications device to receive. The indication of the update schedule may be comprised in assistance system information, for example. In some embodiments, update schedule may be transmitted together with the NES SIB 1.

[0155] In some embodiments, in order for the communications device to determine whether an NES SIB 1 received from the assistance infrastructure equipment is up-to-date, the update schedule indicates one or more of the following:

[0156] — The NES SIB 1 may be updated at T frames or slots or symbols after the assistance infrastructure equipment transmits NES SIB 1 ;

[0157] — The NES SIB 1 may be updated at T frames or slots or symbols after the communications device receives the NES SIB1;

[0158] — A list of one or more transmission timings of NES SIB Is previously transmitted by the assistance infrastructure equipment.

[0159] In some embodiments, the update schedule may indicate that the NES SIB 1 will next be updated at time tl . In some embodiments, where the current time is a short period of time before tl (e.g. within a predefined time period before tl), the communications device may determine to discard the NES SIB1 and wait for the updated NES SIB 1 from the assistance infrastructure equipment (or transmit a request to the assistance infrastructure equipment for the NES SIB1). In some embodiments, where the current time is a long period of time before tl (e.g. outside pre-defined time period before tl), the communications device may determine to use the NES SIB 1 without waiting for an updated NES SIB 1.

[0160] In some embodiments, each NES SIB 1 transmitted by the assistance infrastructure equipment may be transmitted together with an indication of a version of the NES SIB1 (e.g. a version number). In such embodiments, the update schedule may indicate the NES SIB 1 is being updated to each version. Then, the communications device may compare the version of an NES SIB 1 received by the communications device with the update schedule to check if the NES SIB 1 received by the communications device is the most up-to-date NES SIB 1. If not, the communications device may transmit a request to the assistance infrastructure equipment for an updated NES SIB 1.

[0161] The use of an update schedule therefore provides an efficient way of keeping an NES SIB1 at the communications device up-to-date.

[0162] In some embodiments, where the assistance infrastructure equipment is configured to control the time at which the NES SIB 1 is updated, the communications device may implicitly determine that the most recent NES SIB1 received from the assistance infrastructure equipment is up-to-date.

[0163] NES SIB 1 update broadcast

[0164] In some embodiments, the validity indication comprises an indication that the NES SIB 1 is being updated. For example, the NES infrastructure equipment may broadcast the indication that the NES SIB 1 is being updated in the NES cell. The NES infrastructure equipment may transmit the indication that the NES SIB 1 is being updated in the NES cell in response to updating the NES SIB 1.

[0165] The communications device may attempt to receive the validity indication from the NES infrastructure equipment after receiving the NES SIB 1 from the assistance infrastructure equipment. If the communications device receives the validity indication which indicates that the NES SIB 1 is being updated, the communications device may discard a previously received NES SIB 1 from the assistance infrastructure equipment. In such embodiments, the communications device may wait until it receives the updated NES SIB 1. Alternatively, or additionally, the communications device may transmit an indication to the assistance infrastructure equipment that the previously received NES SIB 1 is out-of-date. This indication may alternatively be referred to as a request for an update of the NES SIB 1. In response, the assistance infrastructure equipment may transmit a request for the updated NES SIB 1 to the NES infrastructure equipment, the NES infrastructure equipment may respond by transmitting the updated NES SIB 1 to the assistance infrastructure equipment, and then the assistance infrastructure equipment may transmit the updated NES SIB 1 to the communications device.

[0166] In some embodiments, the validity indication may be transmitted in one or more of:

[0167] — A physical broadcast channel (PBCH) (for example using a spare bit in MIB or using unused information in MIB of NES cell (e.g. k_SSB from ssb-subcarrierOffset in MIB);

[0168] — Group Common Downlink Control Information (GC-DCI);

[0169] — An SIB transmitted by the NES infrastructure equipment.

[0170] 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.

[0171] The following numbered paragraphs provide further example aspects and features of the present technique:

[0172] Paragraph 1. A method of operating a communications device, the method comprising receiving, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmitting a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

[0173] Paragraph 2. A method according to paragraph 1, wherein the receiving the capability indication from the assistance infrastructure equipment by the communications device comprises receiving system information applicable to the assistance cell, the capability indication being comprised in the system information applicable to the assistance cell.

[0174] Paragraph 3. A method according to paragraph 2, wherein the capability indication is comprised in an SIB of the first type applicable to the assistance cell, the SIB of the first type applicable to the assistance cell comprising information required to access the assistance cell.

[0175] Paragraph 4. A method according to paragraph 3, wherein the SIB of the first type applicable to the assistance cell comprises scheduling information indicating a schedule for transmitting one or more other types of SIB applicable to the assistance cell, wherein one of the other types of SIB is an NES support SIB, the NES support SIB indicating that the assistance infrastructure equipment is configured to transmit, in the assistance cell, one or more on-demand SIBs of the first type applicable to one or more respective NES cells provided by one or more respective NES infrastructure equipment.

[0176] Paragraph 5. A method according to paragraph 4, wherein the capability indication is comprised in the scheduling information, the capability indication implicitly indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell by indicating the presence of the schedule for transmitting the NES support SIB in the scheduling information.

[0177] Paragraph 6. A method according to paragraph 4, wherein the capability indication is comprised in the NES support SIB, the capability indication explicitly indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell.

[0178] Paragraph 7. A method according to paragraph 6, wherein the capability indication comprises one or more of: a cell global identity (CGI) of the NES cell, a physical cell identifier (PCI) of the NES cell, and a frequency of the NES cell.

[0179] Paragraph 8. A method according to paragraph 2, wherein the capability indication is comprised in a master information block (MIB) applicable to the assistance cell.

[0180] Paragraph 9. A method according to paragraph 1, wherein the receiving the capability indication from the assistance infrastructure equipment by the communications device comprises receiving, from the assistance infrastructure equipment, a configuration of time and / or frequency resources for transmitting the request for the on-demand SIB, wherein the configuration comprises the capability indication.

[0181] Paragraph 10. A method according to any of paragraphs 1 to 9, wherein the SIB of the first type applicable to the NES cell is a System Information Block Type 1 (SIB1).

[0182] Paragraph 11. A method according to any of paragraphs 1 to 10, wherein the capability indication is a 1- bit indicator.

[0183] Paragraph 12. A method of operating a communications device, the method comprising receiving a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determining, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

[0184] Paragraph 13. A method according to paragraph 12, wherein the validity indication comprises an indication of an update schedule for the on-demand SIB of the first type.

[0185] Paragraph 14. A method according to paragraph 13, wherein the indication of the update schedule for the on-demand SIB of the first type is comprised in system information applicable to the assistance cell. Paragraph 15. A method according to paragraph 12, wherein the validity indication comprises an indication that the on-demand SIB of the first type applicable to the NES cell is being updated. Paragraph 16. A method according to any of paragraphs 12 to 15, wherein the determining by the communication device, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell comprises determining, based on the validity indication, not to use the SIB of the first type applicable to the NES cell for accessing the NES cell, and receiving an updated on-demand SIB of the first type from the assistance infrastructure equipment for accessing the NES cell.

[0186] Paragraph 17. A method according to paragraph 16, wherein the updated on-demand SIB of the first type is received by the communications device in response to the communications device transmitting, to the assistance infrastructure equipment, a request for the updated on-demand SIB of the first type, the request being transmitted in response to the determination by the communications device not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

[0187] Paragraph 18. A method according to any of paragraphs 12 to 17, wherein the validity indication is received from the assistance infrastructure equipment.

[0188] Paragraph 19. A method according to any of paragraphs 12 to 18, wherein the validity indication is received from the NES infrastructure equipment as a broadcast. Paragraph 20. A method of operating assistance infrastructure equipment of a wireless communications network providing an assistance cell for a communications device, the method comprising receiving, by the assistance infrastructure equipment from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmitting the validity indication in the assistance cell.

[0189] Paragraph 21. A method according to paragraph 20, comprising receiving, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmitting the request to the NES infrastructure equipment, receiving, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmitting, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

[0190] Paragraph 22. A method according to paragraph 20 or paragraph 21, wherein the validity indication comprises an indication of an update schedule for the on-demand SIB of the first type applicable to the NES cell.

[0191] Paragraph 23. A method according to any of paragraphs 20 to 22, where assistance infrastructure equipment receives the validity indication from the NES infrastructure equipment via an X2 interface between the assistance infrastructure equipment and the NES infrastructure equipment.

[0192] Paragraph 24. A method of operating network energy saving (NES) infrastructure equipment of a wireless communications network providing an NES cell for a communications device, the method comprising transmitting a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

[0193] Paragraph 25. A method according to paragraph 24, wherein the validity indication is transmitted to the assistance infrastructure equipment.

[0194] Paragraph 26. A method according to paragraph 24, wherein the validity indication is broadcast in the NES cell.

[0195] Paragraph 27. A method of operating assistance infrastructure equipment of a wireless communications network providing an assistance cell for a communications device, the method comprising transmitting, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receiving, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmitting, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receiving, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmitting, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

[0196] Paragraph 28. A communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

[0197] Paragraph 29. A communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determine, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

[0198] Paragraph 30. Assistance infrastructure equipment for a wireless communications network configured to provide an assistance cell for a communications device, the assistance infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit the validity indication in the assistance cell.

[0199] Paragraph 31. Network energy saving (NES) infrastructure equipment for a wireless communications network configured to provide an NES cell for a communications device, the NES infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

[0200] Paragraph 32. Assistance infrastructure equipment for a wireless communications network configured to provide an assistance cell for a communications device, the assistance infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receive, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmit, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receive, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmit, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

[0201] Paragraph 33. Circuitry for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

[0202] Paragraph 34. Circuitry for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determine, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

[0203] Paragraph 35. Circuitry for assistance infrastructure equipment of a wireless communications network configured to provide an assistance cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive, from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit the validity indication in the assistance cell. Paragraph 36. Circuitry for network energy saving (NES) infrastructure equipment for a wireless communications network configured to provide an NES cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to transmit a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

[0204] Paragraph 37. Circuitry for assistance infrastructure equipment of a wireless communications network configured to provide an assistance cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receive, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmit, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receive, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmit, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

[0205] Paragraph 38. A computer program which, when the program is executed by a computer, cause the computer to perform the method of any of paragraphs 1 to 27.

[0206] Paragraph 39. A non-transitory computer-readable storage medium storing a computer program according to paragraph 38.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] References [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0211] [2] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3rdGeneration Partnership Project, vl4.3.0, August 2017. [3] TS 38.470, “3rdGeneration Partnership Project; Technical Specification Group Radio Access

[0212] Network; NG-RAN; Fl general aspects and principles (Release 17)”, 3GPP, V17.4.0, March 2023.

[0213] [4] TS 38.473, “3rdGeneration Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl application protocol (F1AP) (Release 17)”, 3GPP, V17.4.1, April 2023. [5] TS 38.401, “3rdGeneration Partnership Project; Technical Specification Group Radio Access

[0214] Network; NG-RAN; Architecture description (Release 17)”, 3GPP, V17.4.0, March 2023.

[0215] [6] RP-234065, “New WID: Enhancements of network energy savings for NR,” 3GPP TSG RAN Meeting#102, Edinburgh, Scotland, December 1 lth-15th, 2023

[0216] [7] GSMA, 5G energy efficiencies: Green is the new black, f [8] TR 38.864, “Study on network energy savings for NR”, 3GPP, V 18. 1.0, March 2023.

Claims

1. CLAIMSWhat is claimed is:

1. A method of operating a communications device, the method comprising receiving, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmitting a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

2. A method according to claim 1, wherein the receiving the capability indication from the assistance infrastructure equipment by the communications device comprises receiving system information applicable to the assistance cell, the capability indication being comprised in the system information applicable to the assistance cell.

3. A method according to claim 2, wherein the capability indication is comprised in an SIB of the first type applicable to the assistance cell, the SIB of the first type applicable to the assistance cell comprising information required to access the assistance cell.

4. A method according to claim 3, wherein the SIB of the first type applicable to the assistance cell comprises scheduling information indicating a schedule for transmitting one or more other types of SIB applicable to the assistance cell, wherein one of the other types of SIB is an NES support SIB, the NES support SIB indicating that the assistance infrastructure equipment is configured to transmit, in the assistance cell, one or more on-demand SIBs of the first type applicable to one or more respective NES cells provided by one or more respective NES infrastructure equipment.

5. A method according to claim 4, wherein the capability indication is comprised in the scheduling information, the capability indication implicitly indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell by indicating the presence of the schedule for transmitting the NES support SIB in the scheduling information.

6. A method according to claim 4, wherein the capability indication is comprised in the NES support SIB, the capability indication explicitly indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell.

7. A method according to claim 6. wherein the capability indication comprises one or more of: a cell global identity (CGI) of the NES cell, a physical cell identifier (PCI) of the NES cell, and a frequency of the NES cell.

8. A method according to claim 2, wherein the capability indication is comprised in a master information block (MIB) applicable to the assistance cell.

9. A method according to claim 1, wherein the receiving the capability indication from the assistance infrastructure equipment by the communications device comprises receiving, from the assistance infrastructure equipment, a configuration of time and / or frequency resources for transmitting the request for the on-demand SIB, wherein the configuration comprises the capability indication.

10. A method according to claim 1, wherein the SIB of the first type applicable to the NES cell is a System Information Block Type 1 (SIB1).

11. A method according to claim 1, wherein the capability indication is a 1 -bit indicator.

12. A method of operating a communications device, the method comprising receiving a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determining, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

13. A method according to claim 12, wherein the validity indication comprises an indication of an update schedule for the on-demand SIB of the first type.

14. A method according to claim 13, wherein the indication of the update schedule for the on-demand SIB of the first type is comprised in system information applicable to the assistance cell.

15. A method according to claim 12, wherein the validity indication comprises an indication that the on-demand SIB of the first type applicable to the NES cell is being updated.

16. A method according to claim 12, wherein the determining by the communication device, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell comprises determining, based on the validity indication, not to use the SIB of the first type applicable to the NES cell for accessing the NES cell, and receiving an updated on-demand SIB of the first type from the assistance infrastructure equipment for accessing the NES cell.

17. A method according to claim 16, wherein the updated on-demand SIB of the first type is received by the communications device in response to the communications device transmitting, to the assistance infrastructure equipment, a request for the updated on-demand SIB of the first type, the request being transmitted in response to the determination by the communications device not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

18. A method according to claim 12, wherein the validity indication is received from the assistance infrastructure equipment.

19. A method according to claim 12, wherein the validity indication is received from the NES infrastructure equipment as a broadcast.

20. A method of operating assistance infrastructure equipment of a wireless communications network providing an assistance cell for a communications device, the method comprising receiving, by the assistance infrastructure equipment from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system informationblock (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmitting the validity indication in the assistance cell.

21. A method according to claim 20, comprising receiving, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmitting the request to the NES infrastructure equipment, receiving, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmitting, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

22. A method according to claim 20, wherein the validity indication comprises an indication of an update schedule for the on-demand SIB of the first type applicable to the NES cell.

23. A method according to claim 20, where assistance infrastructure equipment receives the validity indication from the NES infrastructure equipment via an X2 interface between the assistance infrastructure equipment and the NES infrastructure equipment.

24. A method of operating network energy saving (NES) infrastructure equipment of a wireless communications network providing an NES cell for a communications device, the method comprising transmitting a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

25. A method according to claim 24, wherein the validity indication is transmitted to the assistance infrastructure equipment.

26. A method according to claim 24, wherein the validity indication is broadcast in the NES cell.

27. A method of operating assistance infrastructure equipment of a wireless communications network providing an assistance cell for a communications device, the method comprising transmitting, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receiving, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmitting, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receiving, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmitting, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

28. A communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver toreceive, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

29. A communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determine, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

30. Assistance infrastructure equipment for a wireless communications network configured to provide an assistance cell for a communications device, the assistance infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit the validity indication in the assistance cell.

31. Network energy saving (NES) infrastructure equipment for a wireless communications network configured to provide an NES cell for a communications device, the NES infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

32. Assistance infrastructure equipment for a wireless communications network configured to provide an assistance cell for a communications device, the assistance infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receive, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmit, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receive, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmit, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

33. Circuitry for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive, from assistance infrastructure equipment of a wireless communications network providing an assistance cell for the communications device, a capability indication, the capability indication indicating whether or not the assistance infrastructure equipment is configured to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell provided by NES infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit a request for the on-demand SIB of the first type applicable to the NES cell to be transmitted, wherein the request is transmitted to the assistance infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is configured to transmit the on-demand SIB of the first type applicable to the NES cell, or the request is transmitted to the NES infrastructure equipment if the capability indication indicates that the assistance infrastructure equipment is not configured to transmit the on-demand SIB of the first type applicable to the NES cell.

34. Circuitry for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to a network energy saving (NES) cell, the NES cell being provided by NES infrastructure equipment of a wireless communications network for a communications device, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network providing an assistance cell for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and determine, based on the validity indication, whether or not to use the on-demand SIB of the first type applicable to the NES cell for accessing the NES cell.

35. Circuitry for assistance infrastructure equipment of a wireless communications network configured to provide an assistance cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals,receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to receive, from a network energy saving (NES) infrastructure equipment of the wireless communications network providing an NES cell for the communications device, a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by the assistance infrastructure equipment, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, and transmit the validity indication in the assistance cell.

36. Circuitry for network energy saving (NES) infrastructure equipment for a wireless communications network configured to provide an NES cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to transmit a validity indication indicating a validity of an on-demand system information block (SIB) of a first type applicable to the NES cell, the on-demand SIB of the first type being transmitted by assistance infrastructure equipment of the wireless communications network, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell.

37. Circuitry for assistance infrastructure equipment of a wireless communications network configured to provide an assistance cell for a communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter and the receiver to transmit, in the assistance cell, an on-demand system information block (SIB) of a first type applicable to a network energy saving cell (NES) cell provided by NES infrastructure equipment of the wireless communications network for the communications device, the on-demand SIB of the first type applicable to the NES cell comprising information required to access the NES cell, receive, from the communications device, a request to update the on-demand SIB of the first type applicable to the NES cell, transmit, to the NES infrastructure equipment, the request to update the on-demand SIB of the first type applicable to the NES cell, receive, from the NES infrastructure equipment, an updated on-demand SIB of the first type applicable to the NES cell, and transmit, in the assistance cell, the updated on-demand SIB of the first type applicable to the NES cell.

38. A computer program which, when the program is executed by a computer, cause the computer to perform the method of claim 1.

39. A non-transitory computer-readable storage medium storing a computer program according to claim 38.

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